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Brown AR, Branthwaite HE, Farahbakhsh ZZ, Mukerjee S, Melugin PR, Song K, Noamany H, Siciliano CA. Structured tracking of alcohol reinforcement (STAR) for basic and translational alcohol research. Mol Psychiatry 2023; 28:1585-1598. [PMID: 36849824 PMCID: PMC10208967 DOI: 10.1038/s41380-023-01994-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 01/26/2023] [Accepted: 02/07/2023] [Indexed: 03/01/2023]
Abstract
There is inherent tension between methodologies developed to address basic research questions in model species and those intended for preclinical to clinical translation: basic investigations require flexibility of experimental design as hypotheses are rapidly tested and revised, whereas preclinical models emphasize standardized protocols and specific outcome measures. This dichotomy is particularly relevant in alcohol research, which spans a diverse range of basic sciences in addition to intensive efforts towards understanding the pathophysiology of alcohol use disorder (AUD). To advance these goals there is a great need for approaches that facilitate synergy across basic and translational areas of nonhuman alcohol research. In male and female mice, we establish a modular alcohol reinforcement paradigm: Structured Tracking of Alcohol Reinforcement (STAR). STAR provides a robust platform for quantitative assessment of AUD-relevant behavioral domains within a flexible framework that allows direct crosstalk between translational and mechanistically oriented studies. To achieve cross-study integration, despite disparate task parameters, a straightforward multivariate phenotyping analysis is used to classify subjects based on propensity for heightened alcohol consumption and insensitivity to punishment. Combining STAR with extant preclinical alcohol models, we delineate longitudinal phenotype dynamics and reveal putative neuro-biomarkers of heightened alcohol use vulnerability via neurochemical profiling of cortical and brainstem tissues. Together, STAR allows quantification of time-resolved biobehavioral processes essential for basic research questions simultaneous with longitudinal phenotyping of clinically relevant outcomes, thereby providing a framework to facilitate cohesion and translation in alcohol research.
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Affiliation(s)
- Alex R Brown
- Department of Pharmacology, Vanderbilt Brain Institute, Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN, 37232, USA
| | - Hannah E Branthwaite
- Department of Pharmacology, Vanderbilt Brain Institute, Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN, 37232, USA
| | - Zahra Z Farahbakhsh
- Department of Pharmacology, Vanderbilt Brain Institute, Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN, 37232, USA
| | - Snigdha Mukerjee
- Department of Pharmacology, Vanderbilt Brain Institute, Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN, 37232, USA
| | - Patrick R Melugin
- Department of Pharmacology, Vanderbilt Brain Institute, Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN, 37232, USA
| | - Keaton Song
- Department of Pharmacology, Vanderbilt Brain Institute, Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN, 37232, USA
| | - Habiba Noamany
- Department of Neurobiology, Harvard Medical School, Boston, MA, USA
| | - Cody A Siciliano
- Department of Pharmacology, Vanderbilt Brain Institute, Vanderbilt Center for Addiction Research, Vanderbilt University, Nashville, TN, 37232, USA.
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2
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Grinevich VP, Krupitsky EM, Gainetdinov RR, Budygin EA. Linking Ethanol-Addictive Behaviors With Brain Catecholamines: Release Pattern Matters. Front Behav Neurosci 2022; 15:795030. [PMID: 34975429 PMCID: PMC8716449 DOI: 10.3389/fnbeh.2021.795030] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 11/26/2021] [Indexed: 12/30/2022] Open
Abstract
Using a variety of animal models that simulate key features of the alcohol use disorder (AUD), remarkable progress has been made in identifying neurochemical targets that may contribute to the development of alcohol addiction. In this search, the dopamine (DA) and norepinephrine (NE) systems have been long thought to play a leading role in comparison with other brain systems. However, just recent development and application of optogenetic approaches into the alcohol research field provided opportunity to identify neuronal circuits and specific patterns of neurotransmission that govern the key components of ethanol-addictive behaviors. This critical review summarizes earlier findings, which initially disclosed catecholamine substrates of ethanol actions in the brain and shows how the latest methodologies help us to reveal the significance of DA and NE release changes. Specifically, we focused on recent optogenetic investigations aimed to reveal cause-effect relationships between ethanol-drinking (seeking and taking) behaviors and catecholamine dynamics in distinct brain pathways. These studies gain the knowledge that is needed for the better understanding addiction mechanisms and, therefore, for development of more effective AUD treatments. Based on the reviewed findings, new messages for researches were indicated, which may have broad applications beyond the field of alcohol addiction.
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Affiliation(s)
- Vladimir P Grinevich
- Department of Neurobiology, Sirius University of Science and Technology, Sochi, Russia
| | - Evgeny M Krupitsky
- V.M. Bekhterev National Medical Research Center for Psychiatry and Neurology, St. Petersburg, Russia.,Laboratory of Clinical Psychopharmacology of Addictions, St.-Petersburg First Pavlov State Medical University, St. Petersburg, Russia
| | - Raul R Gainetdinov
- Department of Neurobiology, Sirius University of Science and Technology, Sochi, Russia.,Institute of Translational Biomedicine and St. Petersburg State University Hospital, St. Petersburg State University, St. Petersburg, Russia
| | - Evgeny A Budygin
- Department of Neurobiology, Sirius University of Science and Technology, Sochi, Russia
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3
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Patwell R, Yang H, Pandey SC, Glover EJ. An operant ethanol self-administration paradigm that discriminates between appetitive and consummatory behaviors reveals distinct behavioral phenotypes in commonly used rat strains. Neuropharmacology 2021; 201:108836. [PMID: 34648771 PMCID: PMC8578460 DOI: 10.1016/j.neuropharm.2021.108836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 10/07/2021] [Accepted: 10/08/2021] [Indexed: 11/30/2022]
Abstract
Alcohol use disorder (AUD) constitutes a major burden to global health. Recently, the translational success of animal models of AUD has come under increased scrutiny. Efforts to refine models to gain a more precise understanding of the neurobiology of addiction are warranted. Appetitive responding for ethanol (seeking) and its consumption (taking) are governed by distinct neurobiological mechanisms. However, consumption is often inferred from appetitive responding in operant ethanol self-administration paradigms, preventing identification of distinct experimental effects on seeking and taking. In the present study, male Long-Evans, Wistar, and Sprague-Dawley rats were trained to lever press for ethanol using a lickometer-equipped system that precisely measures both appetitive and consummatory behavior. Three distinct operant phenotypes emerged during training: 1) Drinkers, who lever press and consume ethanol; 2) Responders, who lever press but consume little to no ethanol; and 3) Non-responders, who do not lever press. While the prevalence of each phenotype differed across strains, appetitive and consummatory behavior was similar across strains within each phenotype. Appetitive and consummatory behaviors were significantly correlated in Drinkers, but not Responders. Analysis of drinking microstructure showed that greater consumption in Drinkers relative to Responders is due to increased incentive for ethanol rather than increased palatability. Importantly, withdrawal from chronic ethanol exposure resulted in a significant increase in appetitive responding in both Drinkers and Responders, but only Drinkers exhibited a concomitant increase in ethanol consumption. Together, these data reveal important strain differences in appetitive and consummatory responding for ethanol and uncover the presence of distinct operant phenotypes.
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Affiliation(s)
- Ryan Patwell
- Center for Alcohol Research in Epigenetics, Department of Psychiatry, University of Illinois at Chicago, Chicago, IL, 60612, USA
| | - Hyerim Yang
- Center for Alcohol Research in Epigenetics, Department of Psychiatry, University of Illinois at Chicago, Chicago, IL, 60612, USA
| | - Subhash C Pandey
- Center for Alcohol Research in Epigenetics, Department of Psychiatry, University of Illinois at Chicago, Chicago, IL, 60612, USA; Jesse Brown VA Medical Center, Chicago, IL, 60612, USA
| | - Elizabeth J Glover
- Center for Alcohol Research in Epigenetics, Department of Psychiatry, University of Illinois at Chicago, Chicago, IL, 60612, USA.
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4
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Huggett SB, Johnson EC, Hatoum AS, Lai D, Srijeyanthan J, Bubier JA, Chesler EJ, Agrawal A, Palmer AA, Edenberg HJ, Palmer RHC. Genes identified in rodent studies of alcohol intake are enriched for heritability of human substance use. Alcohol Clin Exp Res 2021; 45:2485-2494. [PMID: 34751961 DOI: 10.1111/acer.14738] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 09/24/2021] [Accepted: 10/29/2021] [Indexed: 11/29/2022]
Abstract
BACKGROUND Rodent paradigms and human genome-wide association studies (GWAS) on drug use have the potential to provide biological insight into the pathophysiology of addiction. METHODS Using GeneWeaver, we created rodent alcohol and nicotine gene-sets derived from 19 gene expression studies on alcohol and nicotine outcomes. We partitioned the SNP-heritability of these gene-sets using four large human GWAS: 1) alcoholic drinks per week, 2) problematic alcohol use, 3) cigarettes per day and 4) smoking cessation. We benchmarked our findings with curated human alcoholism and nicotine addiction gene-sets and performed specificity analyses using other rodent gene-sets (e.g., locomotor behavior) and other human GWAS (e.g., height). RESULTS The rodent alcohol gene-set was enriched for heritability of drinks per week, cigarettes per day, and smoking cessation, but not problematic alcohol use. However, the rodent nicotine gene-set was not significantly associated with any of these traits. Both rodent gene-sets showed enrichment for several non-substance use GWAS, and the extent of this relationship tended to increase as a function of trait heritability. In general, larger gene-sets demonstrated more significant enrichment. Finally, when evaluating human traits with similar heritabilities, both rodent gene-sets showed greater enrichment for substance use traits. CONCLUSION Our results suggest that rodent gene expression studies can help to identify genes that contribute to heritability of some substance use traits in humans, yet there was less specificity than expected. We outline various limitations, interpretations and considerations for future research.
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Affiliation(s)
- Spencer B Huggett
- Department of Human Genetics, Emory University, Atlanta, GA, USA.,Behavioral Genetics of Addiction Laboratory, Department of Psychology, Emory University, GA University, Atlanta, USA
| | - Emma C Johnson
- Department of Psychiatry, Washington University, St Louis School of Medicine, St. Louis, MO, USA
| | - Alexander S Hatoum
- Department of Psychiatry, Washington University, St Louis School of Medicine, St. Louis, MO, USA
| | - Dongbing Lai
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Jenani Srijeyanthan
- Department of Human Genetics, Emory University, Atlanta, GA, USA.,Behavioral Genetics of Addiction Laboratory, Department of Psychology, Emory University, GA University, Atlanta, USA
| | | | | | - Arpana Agrawal
- Department of Psychiatry, Washington University, St Louis School of Medicine, St. Louis, MO, USA
| | - Abraham A Palmer
- Department of Psychiatry, University of California San Diego, La Jolla, CA, USA.,Institute for Genomic Medicine, University of California San Diego, La Jolla, CA, USA
| | - Howard J Edenberg
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA.,Department of Biochemistry and Molecular Biology, School of Medicine, Indiana University, Indianapolis, IN, USA
| | - Rohan H C Palmer
- Department of Human Genetics, Emory University, Atlanta, GA, USA.,Behavioral Genetics of Addiction Laboratory, Department of Psychology, Emory University, GA University, Atlanta, USA
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5
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Blanco-Gandía MDC, Ródenas-González F, Pascual M, Reguilón MD, Guerri C, Miñarro J, Rodríguez-Arias M. Ketogenic Diet Decreases Alcohol Intake in Adult Male Mice. Nutrients 2021; 13:nu13072167. [PMID: 34202492 PMCID: PMC8308435 DOI: 10.3390/nu13072167] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2021] [Revised: 06/19/2021] [Accepted: 06/22/2021] [Indexed: 01/26/2023] Open
Abstract
The classic ketogenic diet is a diet high in fat, low in carbohydrates, and well-adjusted proteins. The reduction in glucose levels induces changes in the body’s metabolism, since the main energy source happens to be ketone bodies. Recent studies have suggested that nutritional interventions may modulate drug addiction. The present work aimed to study the potential effects of a classic ketogenic diet in modulating alcohol consumption and its rewarding effects. Two groups of adult male mice were employed in this study, one exposed to a standard diet (SD, n = 15) and the other to a ketogenic diet (KD, n = 16). When a ketotic state was stable for 7 days, animals were exposed to the oral self-administration paradigm to evaluate the reinforcing and motivating effects of ethanol. Rt-PCR analyses were performed evaluating dopamine, adenosine, CB1, and Oprm gene expression. Our results showed that animals in a ketotic state displayed an overall decrease in ethanol consumption without changes in their motivation to drink. Gene expression analyses point to several alterations in the dopamine, adenosine, and cannabinoid systems. Our results suggest that nutritional interventions may be a useful complementary tool in treating alcohol-use disorders.
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Affiliation(s)
| | - Francisco Ródenas-González
- Unit of Research Psychobiology of Drug Dependence, Department of Psychobiology, Facultad de Psicología, Universitat de Valencia, Avda. Blasco Ibáñez, 21, 46010 Valencia, Spain; (F.R.-G.); (M.P.); (M.D.R.); (J.M.)
| | - María Pascual
- Unit of Research Psychobiology of Drug Dependence, Department of Psychobiology, Facultad de Psicología, Universitat de Valencia, Avda. Blasco Ibáñez, 21, 46010 Valencia, Spain; (F.R.-G.); (M.P.); (M.D.R.); (J.M.)
- Department of Molecular and Cellular Pathology of Alcohol, Principe Felipe Research Center, C/Eduardo Primo Yúfera 3, 46012 Valencia, Spain;
- Department of Physiology, School of Medicine, Universitat de Valencia, Avda. Blasco Ibáñez, 15, 46010 Valencia, Spain
| | - Marina Daiana Reguilón
- Unit of Research Psychobiology of Drug Dependence, Department of Psychobiology, Facultad de Psicología, Universitat de Valencia, Avda. Blasco Ibáñez, 21, 46010 Valencia, Spain; (F.R.-G.); (M.P.); (M.D.R.); (J.M.)
| | - Consuelo Guerri
- Department of Molecular and Cellular Pathology of Alcohol, Principe Felipe Research Center, C/Eduardo Primo Yúfera 3, 46012 Valencia, Spain;
| | - José Miñarro
- Unit of Research Psychobiology of Drug Dependence, Department of Psychobiology, Facultad de Psicología, Universitat de Valencia, Avda. Blasco Ibáñez, 21, 46010 Valencia, Spain; (F.R.-G.); (M.P.); (M.D.R.); (J.M.)
| | - Marta Rodríguez-Arias
- Unit of Research Psychobiology of Drug Dependence, Department of Psychobiology, Facultad de Psicología, Universitat de Valencia, Avda. Blasco Ibáñez, 21, 46010 Valencia, Spain; (F.R.-G.); (M.P.); (M.D.R.); (J.M.)
- Correspondence: ; Tel.: +34-963864637
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6
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Ballesta A, Alen F, Orio L, Arco R, Vadas E, Decara J, Vargas A, Gómez de Heras R, Ramírez‐López M, Serrano A, Pavón FJ, Suárez J, Rodríguez de Fonseca F. Abrupt cessation of reboxetine along alcohol deprivation results in alcohol intake escalation after reinstatement of drinking. Addict Biol 2021; 26:e12957. [PMID: 32815666 DOI: 10.1111/adb.12957] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 06/10/2020] [Accepted: 07/24/2020] [Indexed: 01/19/2023]
Abstract
Major depression (MD) is a frequent comorbidity in alcohol use disorder (AUD) patients. Antidepressant prescription is often limited by poor clinical outcomes or unwanted side effects in comorbid AUD-MD patients. Recent studies suggest that abrupt cessation of selective serotonin reuptake inhibitors antidepressant treatment increases alcohol consumption after an alcohol deprivation period in rats. However, the appearance of this effect after the treatment with selective noradrenaline reuptake inhibitors (SNRIs) is not known. Here, we report that interruption of subchronic (14 days) treatment with the SNRIs reboxetine (15 mg/kg/day intraperitoneally) resulted in escalation of ethanol intake when the animals resume alcohol self-administration. This effect of reboxetine treatment cessation was associated with a profound deactivation of the endocannabinoid/acylethanolamide signaling system in the prefrontal cortex but not in the dorsal hippocampus, as reflected by the decrease in the protein expression of the cannabinoid CB1 receptor, the PPARα receptor, the 2-arachidonoylglycerol synthesizing enzymes DAGLα and DGALβ, and the endocanabinoid degrading enzyme MAGL. This was associated with dysregulation of the expression of glutamic acid receptors GluN1, GluA1, and mGlu5 in the medial prefrontal cortex and the dorsal hippocampus of the animals exposed to reboxetine. The present results further support the idea that abrupt cessation of antidepressant therapy along alcohol deprivation time can boost alcohol intake after relapse through mechanisms associated with endocannabinoid/glutamate signaling dysregulation. This finding might be relevant for patients suffering AUD/MD comorbidity where antidepressant therapy must be monitored with caution for avoiding unwanted side effects if adherence to the treatment is not fully achieved.
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Affiliation(s)
- Antonio Ballesta
- Departamento de Psicobiología y Metodología en Ciencias del Comportamiento, Facultad de Psicología Universidad Complutense de Madrid Madrid Spain
| | - Francisco Alen
- Departamento de Psicobiología y Metodología en Ciencias del Comportamiento, Facultad de Psicología Universidad Complutense de Madrid Madrid Spain
- Laboratorio de Medicina Regenerativa, Instituto de Investigación Biomédica de Málaga (IBIMA), UGC Salud Mental Hospital Regional Universitario de Málaga Málaga Spain
| | - Laura Orio
- Departamento de Psicobiología y Metodología en Ciencias del Comportamiento, Facultad de Psicología Universidad Complutense de Madrid Madrid Spain
| | - Rocío Arco
- Laboratorio de Medicina Regenerativa, Instituto de Investigación Biomédica de Málaga (IBIMA), UGC Salud Mental Hospital Regional Universitario de Málaga Málaga Spain
| | - Evelyn Vadas
- Laboratorio de Medicina Regenerativa, Instituto de Investigación Biomédica de Málaga (IBIMA), UGC Salud Mental Hospital Regional Universitario de Málaga Málaga Spain
| | - Juan Decara
- Laboratorio de Medicina Regenerativa, Instituto de Investigación Biomédica de Málaga (IBIMA), UGC Salud Mental Hospital Regional Universitario de Málaga Málaga Spain
| | - Antonio Vargas
- Laboratorio de Medicina Regenerativa, Instituto de Investigación Biomédica de Málaga (IBIMA), UGC Salud Mental Hospital Regional Universitario de Málaga Málaga Spain
| | - Raquel Gómez de Heras
- Departamento de Psicobiología y Metodología en Ciencias del Comportamiento, Facultad de Psicología Universidad Complutense de Madrid Madrid Spain
| | - Mayte Ramírez‐López
- Departamento de Psicobiología y Metodología en Ciencias del Comportamiento, Facultad de Psicología Universidad Complutense de Madrid Madrid Spain
| | - Antonia Serrano
- Laboratorio de Medicina Regenerativa, Instituto de Investigación Biomédica de Málaga (IBIMA), UGC Salud Mental Hospital Regional Universitario de Málaga Málaga Spain
| | - Francisco Javier Pavón
- Laboratorio de Medicina Regenerativa, Instituto de Investigación Biomédica de Málaga (IBIMA), UGC Salud Mental Hospital Regional Universitario de Málaga Málaga Spain
| | - Juan Suárez
- Laboratorio de Medicina Regenerativa, Instituto de Investigación Biomédica de Málaga (IBIMA), UGC Salud Mental Hospital Regional Universitario de Málaga Málaga Spain
| | - Fernando Rodríguez de Fonseca
- Departamento de Psicobiología y Metodología en Ciencias del Comportamiento, Facultad de Psicología Universidad Complutense de Madrid Madrid Spain
- Laboratorio de Medicina Regenerativa, Instituto de Investigación Biomédica de Málaga (IBIMA), UGC Salud Mental Hospital Regional Universitario de Málaga Málaga Spain
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7
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Abstract
Animal models of addictive behaviors are useful for uncovering neural mechanisms involved in the development of dependence and for identifying risk factors for drug abuse. One such risk factor is biological sex, which strongly moderates drug self-administration behavior in rodents. Female rodents are more likely to acquire drug self-administration behaviors, consume higher amounts of drug, and reinstate drug-seeking behavior more readily. Despite this female vulnerability, preclinical addiction research has largely been done in male animals. The study of sex differences in rodent models of addictive behavior is increasing, however, as more investigators are choosing to include both male and female animals in experiments. This commentary is meant to serve as an introductory guide for preclinical investigators new to the study of sex differences in addiction. We provide an overview of self-administration models, a broad view of female versus male self-administration behaviors, and suggestions for study design and implementation. Inclusion of female subjects in preclinical addiction research is timely, as problem drug and alcohol use in women is increasing. With proper attention, design, and analysis, the study of sex differences in addiction has the potential to uncover novel neural mechanisms and lead to greater translational success for addiction research. © 2021 Wiley Periodicals LLC.
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Affiliation(s)
- Anna K. Radke
- Department of Psychology and Center for Neuroscience and Behavior, Miami University, Oxford, Ohio
| | - Elizabeth A. Sneddon
- Department of Psychology and Center for Neuroscience and Behavior, Miami University, Oxford, Ohio
| | - Sean C. Monroe
- Department of Psychology and Center for Neuroscience and Behavior, Miami University, Oxford, Ohio
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8
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Holstein SE, Barkell GA, Young MR. Caffeine increases alcohol self-administration, an effect that is independent of dopamine D 2 receptor function. Alcohol 2021; 91:61-73. [PMID: 33429015 DOI: 10.1016/j.alcohol.2020.12.004] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Revised: 12/14/2020] [Accepted: 12/21/2020] [Indexed: 01/09/2023]
Abstract
The rising popularity of alcohol mixed with energy drinks (AmEDs) has become a significant public health concern, with AmED users reporting higher levels of alcohol intake than non-AmED users. One mechanism proposed to explain this heightened level of alcohol intake in AmED users is that the high levels of caffeine found in energy drinks may increase the positive reinforcing properties of alcohol, an effect that may be dependent on interactions between adenosine receptor signaling pathways and the dopamine D2 receptor. Therefore, the purpose of the current study was to confirm whether caffeine does increase the positive reinforcing effects of alcohol using both fixed ratio (FR) and progressive ratio (PR) designs, and to investigate a potential role of the dopamine D2 receptor to caffeine-induced increases in alcohol self-administration. Male Long-Evans rats were trained to self-administer a sweetened alcohol solution (10% v/v alcohol + 2% w/v sucrose) on an FR2 schedule of reinforcement, and the effects of caffeine (0, 5, 10, and 20 mg/kg, i. p. [intraperitoneally]) on the maintenance of alcohol self-administration and alcohol break point were examined. Parallel experiments in rats trained to self-administer sucrose (0.8% w/v) were conducted to determine whether caffeine's reinforcement-enhancing effects extended to a non-drug reinforcer. Caffeine pretreatment (5-10 mg/kg) significantly increased sweetened alcohol self-administration and motivation for a sweetened alcohol reinforcer. However, similar increases in self-administration of a non-drug reinforcer were not observed. Contrary to our hypothesis, the D2 receptor antagonist eticlopride did not block a caffeine-induced increase in sweetened alcohol self-administration, nor did it alter caffeine-induced increases in motivation for a sweetened alcohol reinforcer. Taken together, these results support the hypothesis that caffeine increases the positive reinforcing effects of alcohol, which may explain caffeine-induced increases in alcohol intake. However, the reinforcement-enhancing effects of caffeine appear to be independent of D2 receptor function.
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Affiliation(s)
- Sarah E Holstein
- Department of Psychology, Lycoming College, One College Place, Williamsport, PA, 17701, United States.
| | - Gillian A Barkell
- Department of Psychology, Lycoming College, One College Place, Williamsport, PA, 17701, United States
| | - Megan R Young
- Department of Psychology, Lycoming College, One College Place, Williamsport, PA, 17701, United States
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9
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Vena AA, Zandy SL, Cofresí RU, Gonzales RA. Behavioral, neurobiological, and neurochemical mechanisms of ethanol self-administration: A translational review. Pharmacol Ther 2020; 212:107573. [PMID: 32437827 PMCID: PMC7580704 DOI: 10.1016/j.pharmthera.2020.107573] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/29/2020] [Indexed: 12/16/2022]
Abstract
Alcohol use disorder has multiple characteristics including excessive ethanol consumption, impaired control over drinking behaviors, craving and withdrawal symptoms, compulsive seeking behaviors, and is considered a chronic condition. Relapse is common. Determining the neurobiological targets of ethanol and the adaptations induced by chronic ethanol exposure is critical to understanding the clinical manifestation of alcohol use disorders, the mechanisms underlying the various features of the disorder, and for informing medication development. In the present review, we discuss ethanol's interactions with a variety of neurotransmitter systems, summarizing findings from preclinical and translational studies to highlight recent progress in the field. We then describe animal models of ethanol self-administration, emphasizing the value, limitations, and validity of commonly used models. Lastly, we summarize the behavioral changes induced by chronic ethanol self-administration, with an emphasis on cue-elicited behavior, the role of ethanol-related memories, and the emergence of habitual ethanol seeking behavior.
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Affiliation(s)
- Ashley A Vena
- Department of Psychiatry and Behavioral Neuroscience, University of Chicago, United States of America
| | | | - Roberto U Cofresí
- Psychological Sciences, University of Missouri, United States of America
| | - Rueben A Gonzales
- Division of Pharmacology and Toxicology, College of Pharmacy and Institute for Neuroscience, The University of Texas at Austin, United States of America.
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10
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Deal AL, Bass CE, Grinevich VP, Delbono O, Bonin KD, Weiner JL, Budygin EA. Bidirectional Control of Alcohol-drinking Behaviors Through Locus Coeruleus Optoactivation. Neuroscience 2020; 443:84-92. [PMID: 32707291 DOI: 10.1016/j.neuroscience.2020.07.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 07/10/2020] [Accepted: 07/14/2020] [Indexed: 12/17/2022]
Abstract
The relationship between stress and alcohol-drinking behaviors has been intensively explored; however, neuronal substrates and neurotransmitter dynamics responsible for a causal link between these conditions are still unclear. Here, we optogenetically manipulated locus coeruleus (LC) norepinephrine (NE) activity by applying distinct stimulation protocols in order to explore how phasic and tonic NE release dynamics control alcohol-drinking behaviors. Our results clearly demonstrate contrasting behavioral consequences of LC-NE circuitry activation during low and high frequency stimulation. Specifically, applying tonic stimulation during a standard operant drinking session resulted in increased intake, while phasic stimulation decreased this measure. Furthermore, stimulation during extinction probe trials, when the lever press response was not reinforced, did not significantly alter alcohol-seeking behavior if a tonic pattern was applied. However, phasic stimulation substantially suppressed the number of lever presses, indicating decreased alcohol seeking under the same experimental condition. Given the well-established correlative link between stress and increased alcohol consumption, here we provide the first evidence that tonic LC-NE activity plays a causal role in stress-associated increases in drinking.
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Affiliation(s)
- Alex L Deal
- Department of Neurobiology and Anatomy, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Caroline E Bass
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
| | - Valentina P Grinevich
- Department of Neurobiology and Anatomy, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Osvaldo Delbono
- Department of Internal Medicine, Gerontology, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Keith D Bonin
- Department of Physics, Wake Forest University, Winston-Salem, NC, USA
| | - Jeff L Weiner
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Evgeny A Budygin
- Department of Neurobiology and Anatomy, Wake Forest School of Medicine, Winston-Salem, NC, USA.
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Reguilón MD, Ferrer-Pérez C, Ballestín R, Miñarro J, Rodríguez-Arias M. Voluntary wheel running protects against the increase in ethanol consumption induced by social stress in mice. Drug Alcohol Depend 2020; 212:108004. [PMID: 32408137 DOI: 10.1016/j.drugalcdep.2020.108004] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 04/06/2020] [Accepted: 04/06/2020] [Indexed: 12/11/2022]
Abstract
Previous studies have shown that exposure to social defeat (SD), a model of social stress, produces a long-term increase in the consumption of ethanol, most likely through an increase in the neuroinflammation response. The aim of the present study was to evaluate whether exposure to physical activity in the form of voluntary wheel running (VWR) could block the increase in ethanol consumption and the neuroinflammatory response induced by social stress. Mice were exposed to either 4 sessions of repeated social defeat (RSD) or a non-stressful experience. During the whole procedure, half of the mice were exposed to controlled physical activity, being allowed 1 h access to a low-profile running wheel three times a week. Three weeks after the last RSD, animals started the oral self-administration (SA) of ethanol (6% EtOH) procedure. Biological samples were taken 4 h after the first and the fourth RSD, 3 weeks after the last RSD, and after the SA procedure. Brain tissue (striatum) was used to determine protein levels of the chemokines fractalkine (CX3CL1) and SDF-1 (CXCL12). RSD induced an increase in ethanol consumption and caused greater motivation to obtain ethanol. The striatal levels of CX3CL1 and CXCL12 were also increased after the last RSD. VWR was able to reverse the increase in ethanol intake induced by social stress and the neuroinflammatory response. In conclusion, our results suggest that VWR could be a promising tool to prevent and reduce the detrimental effects induced by social stress.
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Affiliation(s)
- M D Reguilón
- Department of Psychobiology, Facultad De Psicología, Universitat De Valencia, Avda. Blasco Ibáñez, 21, 46010 Valencia, Spain
| | - C Ferrer-Pérez
- Department of Psychobiology, Facultad De Psicología, Universitat De Valencia, Avda. Blasco Ibáñez, 21, 46010 Valencia, Spain
| | - R Ballestín
- Department of Psychobiology, Facultad De Psicología, Universitat De Valencia, Avda. Blasco Ibáñez, 21, 46010 Valencia, Spain
| | - J Miñarro
- Department of Psychobiology, Facultad De Psicología, Universitat De Valencia, Avda. Blasco Ibáñez, 21, 46010 Valencia, Spain
| | - M Rodríguez-Arias
- Department of Psychobiology, Facultad De Psicología, Universitat De Valencia, Avda. Blasco Ibáñez, 21, 46010 Valencia, Spain.
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12
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Johnson KA, Lovinger DM. Allosteric modulation of metabotropic glutamate receptors in alcohol use disorder: Insights from preclinical investigations. ADVANCES IN PHARMACOLOGY (SAN DIEGO, CALIF.) 2020; 88:193-232. [PMID: 32416868 DOI: 10.1016/bs.apha.2020.02.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Metabotropic glutamate (mGlu) receptors are family C G protein-coupled receptors (GPCRs) that modulate neuronal excitability and synaptic transmission throughout the nervous system. Owing to recent advances in development of subtype-selective allosteric modulators of mGlu receptors, individual members of the mGlu receptor family have been proposed as targets for treating a variety of neurological and psychiatric disorders, including substance use disorders. In this chapter, we highlight preclinical evidence that allosteric modulators of mGlu receptors could be useful for reducing alcohol consumption and preventing relapse in alcohol use disorder (AUD). We begin with an overview of the preclinical models that are used to study mGlu receptor involvement in alcohol-related behaviors. Alcohol exposure causes adaptations in both expression and function of various mGlu receptor subtypes, and pharmacotherapies aimed at reversing these adaptations have the potential to reduce alcohol consumption and seeking. Positive allosteric modulators (PAMs) of mGlu2 and negative allosteric modulators of mGlu5 show particular promise for reducing alcohol intake and/or preventing relapse. Finally, this chapter discusses important considerations for translating preclinical findings toward the development of clinically useful drugs, including the potential for PAMs to avoid tolerance issues that are frequently observed with repeated administration of GPCR agonists.
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Affiliation(s)
- Kari A Johnson
- Department of Pharmacology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States.
| | - David M Lovinger
- Laboratory for Integrative Neuroscience, National Institute on Alcohol Abuse and Alcoholism, US National Institutes of Health, Rockville, MD, United States
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Budygin EA, Bass CE, Grinevich VP, Deal AL, Bonin KD, Weiner JL. Opposite Consequences of Tonic and Phasic Increases in Accumbal Dopamine on Alcohol-Seeking Behavior. iScience 2020; 23:100877. [PMID: 32062422 PMCID: PMC7031354 DOI: 10.1016/j.isci.2020.100877] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Revised: 08/27/2019] [Accepted: 01/28/2020] [Indexed: 12/21/2022] Open
Abstract
Despite many years of work on dopaminergic mechanisms of alcohol addiction, much of the evidence remains mostly correlative in nature. Fortunately, recent technological advances have provided the opportunity to explore the causal role of alterations in neurotransmission within circuits involved in addictive behaviors. Here, we address this critical gap in our knowledge by integrating an optogenetic approach and an operant alcohol self-administration paradigm to assess directly how accumbal dopamine (DA) release dynamics influences the appetitive (seeking) component of alcohol-drinking behavior. We show that appetitive reward-seeking behavior in rats trained to self-administer alcohol can be shaped causally by ventral tegmental area-nucleus accumbens (VTA-NAc) DA neurotransmission. Our findings reveal that phasic patterns of DA release within this circuit enhance a discrete measure of alcohol seeking, whereas tonic patterns of stimulation inhibit this behavior. Moreover, we provide mechanistic evidence that tonic-phasic interplay within the VTA-NAc DA circuit underlies these seemingly paradoxical effects. VTA-NAc DA transmission can bidirectionally modulate motivated behavior Optogenetic increases in phasic DA release in the NAc enhance alcohol seeking Optogenetic increases in tonic DA release in the NAc inhibit alcohol seeking Phasic DA release can be decreased by the concurrent tonic activation
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Affiliation(s)
- Evgeny A Budygin
- Department of Neurobiology and Anatomy, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA.
| | - Caroline E Bass
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
| | - Valentina P Grinevich
- Department of Neurobiology and Anatomy, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA
| | - Alex L Deal
- Department of Neurobiology and Anatomy, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, NC 27157, USA
| | - Keith D Bonin
- Department of Physics, Wake Forest University, Winston-Salem, NC, USA
| | - Jeff L Weiner
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, USA
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Huf F, Bandiera S, Müller CB, Gea L, Carvalho FB, Rahmeier FL, Reiter KC, Tortorelli LS, Gomez R, da Cruz Fernandes M. Comparative study on the effects of cigarette smoke exposure, ethanol consumption and association: Behavioral parameters, apoptosis, glial fibrillary acid protein and S100β immunoreactivity in different regions of the rat hippocampus. Alcohol 2019; 77:101-112. [PMID: 30870710 DOI: 10.1016/j.alcohol.2018.08.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 08/15/2018] [Accepted: 08/20/2018] [Indexed: 01/17/2023]
Abstract
Exposure to cigarette smoke and ethanol are proposed to trigger neurotoxicity, apoptosis, and to impair neuronal signaling. However, it is little known how the combination of both might trigger astrogliosis and the morphological changes capable of affecting a differential susceptibility of hippocampal regions to these licit drugs. The present study investigated the chronic effects of exposure to cigarette smoke and/or ethanol on behavioral parameters, apoptosis, and alteration in immunoreactivity of glial fibrillary acid protein (GFAP) and S100β in the CA1, CA3, and dentate gyrus (DG) of the rat hippocampus. Adult male Wistar rats (n = 32) were divided into four groups: vehicle (VE, glucose 3% in water, 10 mL/kg), cigarette smoke (TOB, total 12 cigarettes per day), ethanol (ethanol, 2 g/kg), and cigarette smoke plus ethanol (TOB plus ethanol, total 12 cigarettes per day plus ethanol 2 g/kg) for 54 days. The groups were submitted to tail-flick, open-field, and inhibitory avoidance tasks. The results showed that ethanol per se worsened the short-term memory. The association between TOB and ethanol increased the immunoreactivity of cleaved caspase-3 in the CA3 and DG regions. The TOB plus ethanol group showed a lower immunoreactivity to GFAP in all regions of the hippocampus. In addition, ethanol and TOB per se also reduced the immunoreactivity for GFAP in the DG. Ethanol increased S100β immunoreactivity only in the DG. In conclusion, this study showed that only ethanol worsened short-term memory, and the DG became more susceptible to changes in the markers investigated. This evidence suggests that DG is more sensitive to neurotoxicity induced by cigarette smoke and ethanol.
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Affiliation(s)
- Fernanda Huf
- Postgraduate Program in Pathology, Pathology Research Laboratory, Federal University of Health Sciences of Porto Alegre, Porto Alegre, Brazil
| | - Solange Bandiera
- Postgraduate Program in Pharmacology and Therapeutics, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Carolina B Müller
- Department of Biochemistry, ICBS/Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Luiza Gea
- Postgraduate Program in Pathology, Pathology Research Laboratory, Federal University of Health Sciences of Porto Alegre, Porto Alegre, Brazil
| | - Fabiano B Carvalho
- Postgraduate Program in Pathology, Pathology Research Laboratory, Federal University of Health Sciences of Porto Alegre, Porto Alegre, Brazil
| | - Francine L Rahmeier
- Postgraduate Program in Pathology, Pathology Research Laboratory, Federal University of Health Sciences of Porto Alegre, Porto Alegre, Brazil
| | - Keli C Reiter
- Postgraduate Program in Pathology, Pathology Research Laboratory, Federal University of Health Sciences of Porto Alegre, Porto Alegre, Brazil
| | - Lucas S Tortorelli
- Postgraduate Program in Pathology, Pathology Research Laboratory, Federal University of Health Sciences of Porto Alegre, Porto Alegre, Brazil
| | - Rosane Gomez
- Postgraduate Program in Pharmacology and Therapeutics, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Marilda da Cruz Fernandes
- Postgraduate Program in Pathology, Pathology Research Laboratory, Federal University of Health Sciences of Porto Alegre, Porto Alegre, Brazil.
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Ballesta A, Orio L, Arco R, Vargas A, Romero-Sanchiz P, Nogueira-Arjona R, de Heras RG, Antón M, Ramírez-López M, Serrano A, Pavón FJ, de Fonseca FR, Suárez J, Alen F. Bupropion, a possible antidepressant without negative effects on alcohol relapse. Eur Neuropsychopharmacol 2019; 29:756-765. [PMID: 31064683 DOI: 10.1016/j.euroneuro.2019.03.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 03/04/2019] [Accepted: 03/27/2019] [Indexed: 12/15/2022]
Abstract
RATIONALE the role that antidepressants play on alcohol consumption is not well understood. Previous studies have reported that treatment with a Selective Serotonin Reuptake Inhibitor (SSRIs) increases alcohol consumption in an animal model of relapse, however it is unknown whether this effect holds for other antidepressants such as the atypical dopamine/norepinephrine reuptake inhibitors (SNDRI). OBJECTIVES the main goal of the present study was to compare the effects of two classes of antidepressants drugs, bupropion (SNDRI) and fluoxetine (SSRI), on alcohol consumption during relapse. Since glutamatergic and endocannabinoid signaling systems plays an important role in alcohol abuse and relapse, we also evaluated the effects of both antidepressants onthe expression of the main important genes and proteins of both systems in the prefrontal cortex, a critical brain region in alcohol relapse. METHODS rats were trained to self-administered alcohol. During abstinence, rats received a 14d-treatment with vehicle, fluoxetine (10 mg/kg) or bupropion (20 mg/kg), and we evaluated alcohol consumption during relapse for 3 weeks. Samples of prefrontal cortex were taken to evaluate the mRNA and protein expression of the different components of glutamatergic and endocannabinoid signaling systems. RESULTS fluoxetine treatment induced a long-lasting increase in alcohol consumption during relapse, an effect that was not observed in the case of bupropion treatment. The observed increases in alcohol consumption were accompanied by distinct alterations in the glutamate and endocannabinoid systems. CONCLUSIONS our results suggest that SSRIs can negatively impact alcohol consumption in relapse while SNDRIs have no effects. The observed increase in alcohol consumption are accompanied by functional alterations in the glutamatergic and endocannabinoid systems. This finding could open new strategies for the treatment of depression in patients with alcohol use disorders.
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Affiliation(s)
- Antonio Ballesta
- Departamento de Psicobiología y Metodología en Ciencias del Comportamiento, Facultad de Psicología, Universidad Complutense de Madrid, 28224 Spain
| | - Laura Orio
- Departamento de Psicobiología y Metodología en Ciencias del Comportamiento, Facultad de Psicología, Universidad Complutense de Madrid, 28224 Spain
| | - Rocío Arco
- Laboratorio de Medicina Regenerativa, Instituto de Investigación Biomédica de Málaga (IBIMA), UGC Salud Mental, Hospital Regional Universitario de Málaga, Av. Carlos Haya 82, sótano, Málaga 29010, Spain
| | - Antonio Vargas
- Laboratorio de Medicina Regenerativa, Instituto de Investigación Biomédica de Málaga (IBIMA), UGC Salud Mental, Hospital Regional Universitario de Málaga, Av. Carlos Haya 82, sótano, Málaga 29010, Spain
| | - Pablo Romero-Sanchiz
- Laboratorio de Medicina Regenerativa, Instituto de Investigación Biomédica de Málaga (IBIMA), UGC Salud Mental, Hospital Regional Universitario de Málaga, Av. Carlos Haya 82, sótano, Málaga 29010, Spain; Unidad de Salud Mental, Hospital Universitario Regional de Málaga, Instituto de Investigación Biomédica de Málaga (IBIMA), Spain; Departamento de Personalidad, Evaluación y Tratamientos Psicológicos. Universidad de Málaga, Málaga, Spain
| | - Raquel Nogueira-Arjona
- Unidad de Salud Mental, Hospital Universitario Regional de Málaga, Instituto de Investigación Biomédica de Málaga (IBIMA), Spain; Department of Psychology and Neuroscience, Dalhousie University, Canada
| | - Raquel Gómez de Heras
- Departamento de Psicobiología y Metodología en Ciencias del Comportamiento, Facultad de Psicología, Universidad Complutense de Madrid, 28224 Spain
| | - María Antón
- Departamento de Psicobiología y Metodología en Ciencias del Comportamiento, Facultad de Psicología, Universidad Complutense de Madrid, 28224 Spain
| | - Mayte Ramírez-López
- Departamento de Psicobiología y Metodología en Ciencias del Comportamiento, Facultad de Psicología, Universidad Complutense de Madrid, 28224 Spain
| | - Antonia Serrano
- Laboratorio de Medicina Regenerativa, Instituto de Investigación Biomédica de Málaga (IBIMA), UGC Salud Mental, Hospital Regional Universitario de Málaga, Av. Carlos Haya 82, sótano, Málaga 29010, Spain
| | - Francisco Javier Pavón
- Laboratorio de Medicina Regenerativa, Instituto de Investigación Biomédica de Málaga (IBIMA), UGC Salud Mental, Hospital Regional Universitario de Málaga, Av. Carlos Haya 82, sótano, Málaga 29010, Spain
| | - Fernando Rodríguez de Fonseca
- Departamento de Psicobiología y Metodología en Ciencias del Comportamiento, Facultad de Psicología, Universidad Complutense de Madrid, 28224 Spain; Laboratorio de Medicina Regenerativa, Instituto de Investigación Biomédica de Málaga (IBIMA), UGC Salud Mental, Hospital Regional Universitario de Málaga, Av. Carlos Haya 82, sótano, Málaga 29010, Spain.
| | - Juan Suárez
- Laboratorio de Medicina Regenerativa, Instituto de Investigación Biomédica de Málaga (IBIMA), UGC Salud Mental, Hospital Regional Universitario de Málaga, Av. Carlos Haya 82, sótano, Málaga 29010, Spain.
| | - Francisco Alen
- Departamento de Psicobiología y Metodología en Ciencias del Comportamiento, Facultad de Psicología, Universidad Complutense de Madrid, 28224 Spain; Laboratorio de Medicina Regenerativa, Instituto de Investigación Biomédica de Málaga (IBIMA), UGC Salud Mental, Hospital Regional Universitario de Málaga, Av. Carlos Haya 82, sótano, Málaga 29010, Spain.
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16
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Nieto SJ, Quave CB, Kosten TA. Naltrexone alters alcohol self-administration behaviors and hypothalamic-pituitary-adrenal axis activity in a sex-dependent manner in rats. Pharmacol Biochem Behav 2018; 167:50-59. [PMID: 29486222 PMCID: PMC6011835 DOI: 10.1016/j.pbb.2018.02.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Revised: 02/07/2018] [Accepted: 02/19/2018] [Indexed: 10/18/2022]
Abstract
BACKGROUND The mu-opioid antagonist, naltrexone (NTX), is a FDA-approved treatment for alcohol use disorder (AUD); however, the data on whether it differentially affects males vs. females are mixed. NTX increases hypothalamic-pituitary-adrenal (HPA) axis activity that associates with subjective responses to alcohol and craving in individuals with AUD. The present study tested for sex differences in the ability of NTX to decrease appetitive and consummatory behaviors in rats in operant alcohol self-administration. Because the opioid system and HPA axis are sexually dimorphic, we examined NTX's effect on adrenocorticotropic hormone (ACTH) and corticosterone (CORT) levels. METHODS Male and female Sprague-Dawley rats (n's = 6-8) were trained to lever press for alcohol (10% v/v) under a fixed-ratio 2 schedule of reinforcement. NTX doses (0, 0.1-10 mg/kg) were assessed in tests conducted under a progressive ratio schedule of reinforcement. Separate groups of alcohol and water drinking rats (n's = 8) were used to assess NTX's (10 mg/kg) effects on HPA axis hormones. RESULTS NTX decreased consummatory behaviors for alcohol in a dose-related manner, but not appetitive behaviors in males. In females, NTX decreased appetitive behaviors for alcohol in a dose-dependent manner, but only decreased consummatory behaviors at the highest (10 mg/kg) NTX dose. NTX increased ACTH levels in alcohol drinking females in diestrus, but not in other groups. However, NTX increased CORT levels for longer durations in alcohol drinking males relative to alcohol drinking females in diestrus. CONCLUSIONS Our findings suggest that NTX selectively reduces consummatory behaviors for alcohol in males and appetitive behaviors in females, while also showing differential sex effects on HPA hormones.
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Affiliation(s)
- Steven J Nieto
- University of Houston, Department of Psychology & Texas Institute for Measurement, Evaluation and Statistics (TIMES), Houston, TX 77204-6022, United States
| | - Cana B Quave
- University of Houston, Department of Psychology & Texas Institute for Measurement, Evaluation and Statistics (TIMES), Houston, TX 77204-6022, United States
| | - Therese A Kosten
- University of Houston, Department of Psychology & Texas Institute for Measurement, Evaluation and Statistics (TIMES), Houston, TX 77204-6022, United States.
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Blegen MB, da Silva E Silva D, Bock R, Morisot N, Ron D, Alvarez VA. Alcohol operant self-administration: Investigating how alcohol-seeking behaviors predict drinking in mice using two operant approaches. Alcohol 2018; 67:23-36. [PMID: 29310048 PMCID: PMC5939586 DOI: 10.1016/j.alcohol.2017.08.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Revised: 07/27/2017] [Accepted: 08/10/2017] [Indexed: 02/07/2023]
Abstract
Alcohol operant self-administration paradigms are critical tools for studying the neural circuits implicated in both alcohol-seeking and consummatory behaviors and for understanding the neural basis underlying alcohol-use disorders. In this study, we investigate the predictive value of two operant models of oral alcohol self-administration in mice, one in which alcohol is delivered into a cup following nose-poke responses with no accurate measurement of consumed alcohol solution, and another paradigm that provides access to alcohol via a sipper tube following lever presses and where lick rate and consumed alcohol volume can be measured. The goal was to identify a paradigm where operant behaviors such as lever presses and nose pokes, as well as other tracked behavior such as licks and head entries, can be used to reliably predict blood alcohol concentration (BAC). All mice were first exposed to alcohol in the home cage using the "drinking in the dark" (DID) procedure for 3 weeks and then were trained in alcohol self-administration using either of the operant paradigms for several weeks. Even without sucrose fading or food pre-training, mice acquired alcohol self-administration with both paradigms. However, neither lever press nor nose-poke rates were good predictors of alcohol intake or BAC. Only the lick rate and consumed alcohol were consistently and significantly correlated with BAC. Using this paradigm that accurately measures alcohol intake, unsupervised cluster analysis revealed three groups of mice: high-drinking (43%), low-drinking (37%), and non-drinking mice (20%). High-drinking mice showed faster acquisition of operant responding and achieved higher BACs than low-drinking mice. Lick rate and volume consumed varied with the alcohol concentration made available only for high- and low-drinking mice, but not for non-drinking mice. In addition, high- and low-drinking mice showed similar patterns during extinction and significant cue-induced reinstatement of seeking. Only high-drinking mice showed insensitivity to quinine adulteration, indicating a willingness to drink alcohol despite pairing with aversive stimuli. Thus, this study shows that relying on active presses is not an accurate determination of drinking behavior in mice. Only paradigms that allow for accurate measurements of consumed alcohol and/or lick rate are valid models of operant alcohol self-administration, where compulsive-like drinking could be accurately determined based on changes in alcohol intake when paired with bitter-tasting stimuli.
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Affiliation(s)
- Mariah B Blegen
- Laboratory on Neurobiology of Compulsive Behaviors, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD 20892, USA
| | - Daniel da Silva E Silva
- Laboratory on Neurobiology of Compulsive Behaviors, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD 20892, USA; Institute of Biological Sciences, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil; CAPES Foundation, Ministry of Education of Brazil, Brasília, DF, 70.040-020, Brazil
| | - Roland Bock
- Laboratory on Neurobiology of Compulsive Behaviors, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD 20892, USA
| | - Nadege Morisot
- Department of Neurology, University of California San Francisco, San Francisco, CA 94143-0663, USA
| | - Dorit Ron
- Department of Neurology, University of California San Francisco, San Francisco, CA 94143-0663, USA
| | - Veronica A Alvarez
- Laboratory on Neurobiology of Compulsive Behaviors, National Institute on Alcohol Abuse and Alcoholism, NIH, Bethesda, MD 20892, USA.
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18
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Deal AL, Konstantopoulos JK, Weiner JL, Budygin EA. Exploring the consequences of social defeat stress and intermittent ethanol drinking on dopamine dynamics in the rat nucleus accumbens. Sci Rep 2018; 8:332. [PMID: 29321525 PMCID: PMC5762836 DOI: 10.1038/s41598-017-18706-y] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Accepted: 12/15/2017] [Indexed: 12/16/2022] Open
Abstract
The current study aimed to explore how presynaptic dopamine (DA) function is altered following brief stress episodes and chronic ethanol self-administration and whether these neuroadaptations modify the acute effects of ethanol on DA dynamics. We used fast-scan cyclic voltammetry to evaluate changes in DA release and uptake parameters in rat nucleus accumbens brain slices by analyzing DA transients evoked through single pulse electrical stimulation. Adult male rats were divided into four groups: ethanol-naïve or ethanol drinking (six week intermittent two-bottle choice) and stressed (mild social defeat) or nonstressed. Results revealed that the mild stress significantly increased DA release and uptake in ethanol-naïve subjects, compared to nonstressed controls. Chronic ethanol self-administration increased the DA uptake rate and occluded the effects of stress on DA release dynamics. Bath-applied ethanol decreased stimulated DA efflux in a concentration-dependent manner in all groups; however, the magnitude of this effect was blunted by either stress or chronic ethanol, or by a combination of both procedures. Together, these findings suggest that stress and ethanol drinking may promote similar adaptive changes in accumbal presynaptic DA release measures and that these changes may contribute to the escalation in ethanol intake that occurs during the development of alcohol use disorder.
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Affiliation(s)
- Alex L Deal
- Department of Neurobiology and Anatomy, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | | | - Jeff L Weiner
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | - Evgeny A Budygin
- Department of Neurobiology and Anatomy, Wake Forest School of Medicine, Winston-Salem, NC, USA. .,Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg, Russia.
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19
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Bell RL, Hauser SR, Liang T, Sari Y, Maldonado-Devincci A, Rodd ZA. Rat animal models for screening medications to treat alcohol use disorders. Neuropharmacology 2017; 122:201-243. [PMID: 28215999 PMCID: PMC5659204 DOI: 10.1016/j.neuropharm.2017.02.004] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2017] [Revised: 02/02/2017] [Accepted: 02/05/2017] [Indexed: 01/21/2023]
Abstract
The purpose of this review is to present animal research models that can be used to screen and/or repurpose medications for the treatment of alcohol abuse and dependence. The focus will be on rats and in particular selectively bred rats. Brief introductions discuss various aspects of the clinical picture, which provide characteristics of individuals with alcohol use disorders (AUDs) to model in animals. Following this, multiple selectively bred rat lines will be described and evaluated in the context of animal models used to screen medications to treat AUDs. Next, common behavioral tests for drug efficacy will be discussed particularly as they relate to stages in the addiction cycle. Tables highlighting studies that have tested the effects of compounds using the respective techniques are included. Wherever possible the Tables are organized chronologically in ascending order to describe changes in the focus of research on AUDs over time. In general, high ethanol-consuming selectively bred rats have been used to test a wide range of compounds. Older studies usually followed neurobiological findings in the selected lines that supported an association with a propensity for high ethanol intake. Most of these tests evaluated the compound's effects on the maintenance of ethanol drinking. Very few compounds have been tested during ethanol-seeking and/or relapse and fewer still have assessed their effects during the acquisition of AUDs. Overall, while a substantial number of neurotransmitter and neuromodulatory system targets have been assessed; the roles of sex- and age-of-animal, as well as the acquisition of AUDs, ethanol-seeking and relapse continue to be factors and behaviors needing further study. This article is part of the Special Issue entitled "Alcoholism".
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Affiliation(s)
- Richard L Bell
- Indiana University School of Medicine, Department of Psychiatry, Indianapolis, IN 46202, USA.
| | - Sheketha R Hauser
- Indiana University School of Medicine, Department of Psychiatry, Indianapolis, IN 46202, USA
| | - Tiebing Liang
- Indiana University School of Medicine, Department of Gastroenterology, Indianapolis, IN 46202, USA
| | - Youssef Sari
- University of Toledo, Department of Pharmacology, Toledo, OH 43614, USA
| | | | - Zachary A Rodd
- Indiana University School of Medicine, Department of Psychiatry, Indianapolis, IN 46202, USA
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20
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Orexin/hypocretin-1 receptor antagonism reduces ethanol self-administration and reinstatement selectively in highly-motivated rats. Brain Res 2016; 1654:34-42. [PMID: 27771284 DOI: 10.1016/j.brainres.2016.10.018] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 10/17/2016] [Accepted: 10/18/2016] [Indexed: 12/18/2022]
Abstract
The orexin/hypocretin (ORX) system regulates motivation for natural rewards and drugs of abuse such as alcohol. ORX receptor antagonists, most commonly OX1R antagonists including SB-334867 (SB), decrease alcohol drinking, self-administration and reinstatement in both genetically-bred alcohol-preferring and outbred strains of rats. Importantly, levels of alcohol seeking and drinking in outbred rats are variable, as they are in humans. We have shown that OX1R antagonism selectively decreases homecage alcohol drinking in high-, but not low-alcohol-preferring rats. It is unknown, however, whether this effect is selective to homecage drinking or whether it also applies to alcohol seeking paradigms such as self-administration and reinstatement following extinction, in which motivation is high in the absence of alcohol. Here we trained Sprague Dawley rats to self-administer 20% ethanol paired with a light-tone cue on an FR3 regimen. Rats were then extinguished and subjected to cue-induced reinstatement. Rats were segregated into high- and low-ethanol-responding groups (HR and LR) based on self-administration levels. During self-administration and cue-induced reinstatement, rats were given SB or vehicle prior to ethanol seeking. In both conditions, OX1R antagonism decreased responding selectively in HR, but not LR rats. There were no non-specific effects of SB treatment on arousal or general behavior. These data indicate that ORX signaling at the OX1R receptor specifically regulates high levels of motivation for alcohol, even in the absence of direct alcohol reinforcement. This implicates the ORX system in the pathological motivation underlying alcohol abuse and alcoholism and demonstrates that the OX1R may be an important target for treating alcohol abuse.
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Butler TR, Karkhanis AN, Jones SR, Weiner JL. Adolescent Social Isolation as a Model of Heightened Vulnerability to Comorbid Alcoholism and Anxiety Disorders. Alcohol Clin Exp Res 2016; 40:1202-14. [PMID: 27154240 DOI: 10.1111/acer.13075] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Accepted: 03/24/2016] [Indexed: 01/01/2023]
Abstract
Individuals diagnosed with anxiety-related illnesses are at increased risk of developing alcoholism, exhibit a telescoped progression of this disease and fare worse in recovery, relative to alcoholics that do not suffer from a comorbid anxiety disorder. Similarly, preclinical evidence supports the notion that stress and anxiety represent major risk factors for the development of alcohol use disorder (AUD). Despite the importance of understanding the link between anxiety and alcoholism, much remains unknown about the neurobiological substrates underlying this relationship. One stumbling block has been the lack of animal models that reliably reproduce the spectrum of behaviors associated with increased vulnerability to these diseases. Here, we review the literature that has examined the behavioral and neurobiological outcomes of a simple rodent adolescent social isolation procedure and discuss its validity as a model of vulnerability to comorbid anxiety disorders and alcoholism. Recent studies have provided strong evidence that adolescent social isolation of male rats leads to the expression of a variety of behaviors linked with increased vulnerability to anxiety and/or AUD, including deficits in sensory gating and fear extinction, and increases in anxiety measures and ethanol drinking. Neurobiological studies are beginning to identify mesolimbic adaptations that may contribute to the behavioral phenotype engendered by this model. Some of these changes include increased excitability of ventral tegmental area dopamine neurons and pyramidal cells in the basolateral amygdala and significant alterations in baseline and stimulated catecholamine signaling. A growing body of evidence suggests that adolescent social isolation may represent a reliable rodent model of heightened vulnerability to anxiety disorders and alcoholism in male rats. These studies provide initial support for the face, construct, and predictive validity of this model and highlight its utility in identifying neurobiological adaptations associated with increased risk of developing these disorders.
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Affiliation(s)
- Tracy R Butler
- Department of Psychology , University of Dayton, Dayton, Ohio
| | - Anushree N Karkhanis
- Department of Physiology and Pharmacology , Wake Forest School of Medicine, Winston Salem, North Carolina
| | - Sara R Jones
- Department of Physiology and Pharmacology , Wake Forest School of Medicine, Winston Salem, North Carolina
| | - Jeffrey L Weiner
- Department of Physiology and Pharmacology , Wake Forest School of Medicine, Winston Salem, North Carolina
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22
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Bell RL, Hauser S, Rodd ZA, Liang T, Sari Y, McClintick J, Rahman S, Engleman EA. A Genetic Animal Model of Alcoholism for Screening Medications to Treat Addiction. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2016; 126:179-261. [PMID: 27055615 PMCID: PMC4851471 DOI: 10.1016/bs.irn.2016.02.017] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The purpose of this review is to present up-to-date pharmacological, genetic, and behavioral findings from the alcohol-preferring P rat and summarize similar past work. Behaviorally, the focus will be on how the P rat meets criteria put forth for a valid animal model of alcoholism with a highlight on its use as an animal model of polysubstance abuse, including alcohol, nicotine, and psychostimulants. Pharmacologically and genetically, the focus will be on the neurotransmitter and neuropeptide systems that have received the most attention: cholinergic, dopaminergic, GABAergic, glutamatergic, serotonergic, noradrenergic, corticotrophin releasing hormone, opioid, and neuropeptide Y. Herein, we sought to place the P rat's behavioral and neurochemical phenotypes, and to some extent its genotype, in the context of the clinical literature. After reviewing the findings thus far, this chapter discusses future directions for expanding the use of this genetic animal model of alcoholism to identify molecular targets for treating drug addiction in general.
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Affiliation(s)
- R L Bell
- Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, United States.
| | - S Hauser
- Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, United States
| | - Z A Rodd
- Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, United States
| | - T Liang
- Indiana University School of Medicine, Indianapolis, IN, United States
| | - Y Sari
- University of Toledo, Toledo, OH, United States
| | - J McClintick
- Center for Medical Genomics, Indiana University School of Medicine, Indianapolis, IN, United States
| | - S Rahman
- Department of Pharmaceutical Sciences, South Dakota State University, Brookings, SD, United States
| | - E A Engleman
- Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, IN, United States
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Ethanol self-administration in mice under a second-order schedule. Alcohol 2015; 49:561-70. [PMID: 26254963 DOI: 10.1016/j.alcohol.2015.06.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Revised: 06/09/2015] [Accepted: 06/20/2015] [Indexed: 11/23/2022]
Abstract
Long Fixed-Interval (FI) schedules, particularly second-order schedules, can engender substantial responding before drug or ethanol delivery that is uninfluenced by the direct effects of the drug or ethanol. Thus, these schedules can be used to study the effects of medications upon drug- or ethanol-seeking, uninfluenced by the direct effects of the self-administered drug or ethanol. Long FI second-order schedules are frequently used in primates and occasionally in rats. Under second-order schedules, completion of one response requirement, e.g., a Fixed Ratio 10 (FR10:S), produces a brief stimulus presentation, e.g., a 1-s 80-dB 4-kHZ tone, and this FR10:S serves as the response unit under another schedule, e.g., an FI 1800-s. Thus, the first FR10 completed after 1800 s would result in delivery both of the tone and of reinforcement, e.g., 10 × 0.01 mL 16% (w/v) ethanol. To examine if such schedules could be effectively used in mice, which have advantages in neurobiological and genetic studies, we trained eight C57BL/6J mice to respond under the schedule just described. This schedule maintained substantial responding. The temporal pattern of behavior was typical of an FI schedule with responding accelerating across the interval. We also examined the effects of acute and chronic administration of fluvoxamine on this responding, and these were modest. Finally, we examined responding when alcohol and/or tone deliveries were withheld, and found that extinction occurred most rapidly when both were withheld. This work demonstrates that long FI schedules of ethanol delivery may be useful in studying ethanol seeking in mice.
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Randall PA, Jaramillo AA, Frisbee S, Besheer J. The role of varenicline on alcohol-primed self-administration and seeking behavior in rats. Psychopharmacology (Berl) 2015; 232:2443-54. [PMID: 25656746 PMCID: PMC4482789 DOI: 10.1007/s00213-015-3878-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 01/21/2015] [Indexed: 12/30/2022]
Abstract
RATIONALE Varenicline, a smoking-cessation agent, may be useful in treating alcohol use disorders. An important consideration when studying factors that influence drinking/relapse is influence of the pharmacological effects of alcohol on these behaviors. Pre-exposure to alcohol (priming) can increase craving, drinking, and seeking behaviors. OBJECTIVES The primary goal of this work was to determine the effects of varenicline on alcohol-primed self-administration and seeking behavior in male Long-Evans rats. METHODS First, we assessed whether varenicline (0, 0.3, 1, 3 mg/kg, IP) has alcohol-like discriminative stimulus effects and whether varenicline alters sensitivity to alcohol in rats trained to discriminate a moderate alcohol dose (1 g/kg, IG) vs. water. Second, animals trained to self-administer alcohol underwent assessments to test the effects of: (i) varenicline (0, 0.3, 1, 3 mg/kg, IP) on self-administration, (ii) alcohol priming (0, 0.3, 1 g/kg, IG) on self-administration and seeking behavior, and (iii) varenicline (1 mg/kg) in combination with alcohol priming (1 g/kg) on these behaviors. RESULTS Varenicline did not substitute for alcohol but disrupted the expression of sensitivity to alcohol. Varenicline decreased self-administration but only at a motor-impairing dose (3 mg/kg). Alcohol priming decreased self-administration and seeking behavior. Varenicline (1 mg/kg) blocked this effect under self-administration conditions, but not seeking conditions, which effectively resulted in increased alcohol intake. CONCLUSIONS These findings suggest the importance of further behavioral and mechanistic studies to evaluate the use of varenicline in treating alcohol use disorders and its potential impact on drinking patterns in smokers using varenicline as a smoking-cessation aid.
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Affiliation(s)
- Patrick A. Randall
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-7178, USA
| | - Anel A. Jaramillo
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-7178, USA
- Curriculum in Neurobiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-7178, USA
| | - Suzanne Frisbee
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-7178, USA
| | - Joyce Besheer
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-7178, USA
- Curriculum in Neurobiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-7178, USA
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, 27599-7178, USA
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Lim YW, Meyer NP, Shah AS, Budde MD, Stemper BD, Olsen CM. Voluntary Alcohol Intake following Blast Exposure in a Rat Model of Mild Traumatic Brain Injury. PLoS One 2015; 10:e0125130. [PMID: 25910266 PMCID: PMC4409117 DOI: 10.1371/journal.pone.0125130] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 03/11/2015] [Indexed: 12/24/2022] Open
Abstract
Alcoholism is a frequent comorbidity following mild traumatic brain injury (mTBI), even in patients without a previous history of alcohol dependence. Despite this correlational relationship, the extent to which the neurological effects of mTBI contribute to the development of alcoholism is unknown. In this study, we used a rodent blast exposure model to investigate the relationship between mTBI and voluntary alcohol drinking in alcohol naïve rats. We have previously demonstrated in Sprague Dawley rats that blast exposure leads to microstructural abnormalities in the medial prefrontal cortex (mPFC) and other brain regions that progress from four to thirty days. The mPFC is a brain region implicated in alcoholism and drug addiction, although the impact of mTBI on drug reward and addiction using controlled models remains largely unexplored. Alcohol naïve Sprague Dawley rats were subjected to a blast model of mTBI (or sham conditions) and then tested in several common measures of voluntary alcohol intake. In a seven-week intermittent two-bottle choice alcohol drinking test, sham and blast exposed rats had comparable levels of alcohol intake. In a short access test session at the conclusion of the two-bottle test, blast rats fell into a bimodal distribution, and among high intake rats, blast treated animals had significantly elevated intake compared to shams. We found no effect of blast when rats were tested for an alcohol deprivation effect or compulsive drinking in a quinine adulteration test. Throughout the experiment, alcohol drinking was modest in both groups, consistent with other studies using Sprague Dawley rats. In conclusion, blast exposure had a minimal impact on overall alcohol intake in Sprague Dawley rats, although intake was increased in a subpopulation of blast animals in a short access session following intermittent access exposure.
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Affiliation(s)
- Yi Wei Lim
- Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Department of Pharmacology & Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Nathan P. Meyer
- Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Department of Pharmacology & Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
| | - Alok S. Shah
- Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, WI, United States of America
| | - Matthew D. Budde
- Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, WI, United States of America
| | - Brian D. Stemper
- Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, WI, United States of America
| | - Christopher M. Olsen
- Neuroscience Research Center, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- Department of Pharmacology & Toxicology, Medical College of Wisconsin, Milwaukee, Wisconsin, United States of America
- * E-mail:
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26
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Acetaldehyde self-administration by a two-bottle choice paradigm: consequences on emotional reactivity, spatial learning, and memory. Alcohol 2015; 49:139-48. [PMID: 25636827 DOI: 10.1016/j.alcohol.2015.01.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Acetaldehyde, the first alcohol metabolite, is responsible for many pharmacological effects that are not clearly distinguishable from those exerted by its parent compound. It alters motor performance, induces reinforced learning and motivated behavior, and produces different reactions according to the route of administration and the relative accumulation in the brain or in the periphery. The effective activity of oral acetaldehyde represents an unresolved field of inquiry that deserves further investigation. Thus, this study explores the acquisition and maintenance of acetaldehyde drinking behavior in adult male rats, employing a two-bottle choice paradigm for water and acetaldehyde solution (from 0.9% to 3.2% v/v), over 8 weeks. The behavioral consequences exerted by chronic acetaldehyde intake are assessed by a set of different tests: trials in an open-field arena and elevated-plus maze provided information on both general motor and explorative activity, and anxiety-driven behavioral responses. The Morris water maze allowed the exploration of cognitive processes such as spatial learning and memory. Determination of acetaldehyde levels in the brain was carried out at the end of the drinking paradigm. Our results indicate that rats exposed for the first time to acetaldehyde at 0.9% displayed a regular and stable daily drinking pattern that reached higher values and a "peaks and drops" shaped-trend when acetaldehyde concentration was increased to 3.2%. Accordingly, an increase in acetaldehyde levels in the brain was determined compared to non-acetaldehyde drinking rats. Acetaldehyde intake during the free-choice paradigm exerted an anxiogenic response in the open-field arena and elevated-plus maze, which in turn correlates with an enhancement in cognitive flexibility and spatial orientation skills, when an adaptive response to a stressful environmental challenge was required. These findings further support the idea that acetaldehyde is indeed a centrally active and behaviorally relevant metabolite of alcohol.
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27
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Individual differences in risk-related behaviors and voluntary alcohol intake in outbred Wistar rats. Behav Pharmacol 2014; 25:206-15. [PMID: 24776488 DOI: 10.1097/fbp.0000000000000036] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Some personality traits and comorbid psychiatric diseases are linked to a propensity for excessive alcohol drinking. The objective of this study was to investigate the association between individual differences in risk-related behaviors, voluntary alcohol intake and preference. Outbred male Wistar rats were tested in a novel open field, followed by assessment of behavioral profiles using the multivariate concentric square field (MCSF) test. Animals were classified into high risk taking and low risk taking on the basis of open-field behavior and into high risk-assessing (HRA) and low risk-assessing (LRA) on the basis of the MCSF profile. Finally, voluntary alcohol intake was investigated using intermittent access to 20% ethanol and water for 5 weeks. Only minor differences in voluntary alcohol intake were found between high risk taking and low risk taking. Differences between HRA and LRA rats were more evident, with higher intake and increased intake over time in HRA relative to LRA rats. Thus, individual differences in risk-assessment behavior showed greater differences in voluntary alcohol intake than risk taking. The findings may relate to human constructs of decision-making and risk taking associated with a predisposition to rewarding and addictive behaviors. Further studies are needed to clarify the relationship between risk-related behaviors, including risk-assessment behavior, and liability for excessive alcohol intake.
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28
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Mead AN. Appropriate experimental approaches for predicting abuse potential and addictive qualities in preclinical drug discovery. Expert Opin Drug Discov 2014; 9:1281-91. [PMID: 25176123 DOI: 10.1517/17460441.2014.956077] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
INTRODUCTION Drug abuse is an increasing social and public health issue, putting the onus on drug developers and regulatory agencies to ensure that the abuse potential of novel drugs is adequately assessed prior to product launch. AREAS COVERED This review summarizes the core preclinical data that frequently contribute to building an understanding of abuse potential for a new molecular entity, in addition to highlighting models that can provide increased resolution regarding the level of risk. Second, an important distinction between abuse potential and addiction potential is drawn, with comments on how preclinical models can inform on each. EXPERT OPINION While the currently adopted preclinical models possess strong predictive validity, there are areas for future refinement and research. These areas include a more refined use of self-administration models to assess relative reinforcement; and the need for open innovation in pursuing improvements. There is also the need for careful scientifically driven application of models rather than a standardization of methodologies, and the need to explore the opportunities that may exist for enhancing the value of physical dependence and withdrawal studies by focusing on withdrawal-induced drug seeking, rather than broad symptomology.
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Affiliation(s)
- Andy N Mead
- Global Safety Pharmacology, Drug Safety Research and Development, Pfizer Worldwide Research and Development , Eastern Point Road, MS 8274-1232, Groton, CT 06340 , USA
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29
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McCool BA, Chappell AM. Persistent enhancement of ethanol drinking following a monosodium glutamate-substitution procedure in C57BL6/J and DBA/2J mice. Alcohol 2014; 48:55-61. [PMID: 24355071 DOI: 10.1016/j.alcohol.2013.10.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 10/29/2013] [Accepted: 10/29/2013] [Indexed: 11/17/2022]
Abstract
Inbred mouse strains such as C57BL/6J (B6) and DBA/2J (D2) and related strains have been used extensively to help identify genetic controls for a number of ethanol-related behaviors, including acute intoxication and sensitivity to repeated exposures. The disparate ethanol drinking behaviors of B6 mice expressing high-drinking/preference and D2 mice expressing low-drinking/preference have yielded considerable insight into the heritable control of alcohol drinking. However, the B6-high and D2-low drinking phenotypes are contrasted with ethanol-conditioned reward-like behaviors, which are robustly expressed by D2 mice and considerably less expressed by B6 mice. This suggests that peripheral factors, chiefly ethanol taste, may help drive ethanol drinking by these and related strains, which complicates mouse genetic studies designed to understand the relationships between reward-related behaviors and ethanol drinking. Traditional approaches such as the sucrose/saccharin-substitution procedure that normally accentuate ethanol drinking in rodents have had limited success in low drinking/preferring mice such as the D2 line. This may be due to allelic variations of the sweet taste receptor subunit, expressed by many ethanol low-drinking/preferring strains, which would limit the utility of these types of substitution approaches. We have recently shown (McCool & Chappell, 2012) that monosodium glutamate (MSG), the primary component of umami taste, can be used in a substitution procedure to initiate ethanol drinking in both B6 and D2 mice that greatly surpasses that initiated by a more traditional sucrose-substitution procedure. In this study, we show that ethanol drinking initiated by MSG substitution in D2 mice, but not sucrose substitution, can persist for several weeks following removal of the flavor. These findings further illustrate the utility of MSG substitution to initiate ethanol drinking in distinct mouse strains.
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Affiliation(s)
- Brian A McCool
- Department of Physiology & Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157 USA.
| | - Ann M Chappell
- Department of Physiology & Pharmacology, Wake Forest School of Medicine, Winston-Salem, NC 27157 USA
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30
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Abstract
Alcoholism (alcohol dependence and alcohol use disorder, AUD) is quintessentially behavioral in nature. AUD is behaviorally and genetically complex. This review discusses behavioral assessment of alcohol sensitivity, tolerance, dependence, withdrawal, and reinforcement. The focus is on using laboratory animal models to explore genetic contributions to individual differences in alcohol responses. Rodent genetic animal models based on selective breeding for high vs low alcohol response, and those based on the use of inbred strains, are reviewed. Genetic strategies have revealed the complexity of alcohol responses where genetic influences on multiple alcohol-related behaviors are mostly discrete. They have also identified areas where genetic influences are consistent across behavioral assays and have been used to model genetic differences among humans at different risk for AUD.
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Affiliation(s)
- John C Crabbe
- Portland Alcohol Research Center and Department of Behavioral Neuroscience, Oregon Health & Science University, Portland, OR, USA.
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31
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Crabbe JC. Rodent models of genetic contributions to motivation to abuse alcohol. NEBRASKA SYMPOSIUM ON MOTIVATION. NEBRASKA SYMPOSIUM ON MOTIVATION 2014; 61:5-29. [PMID: 25306777 PMCID: PMC4988659 DOI: 10.1007/978-1-4939-0653-6_2] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
In summary, there are remarkably few studies focused on the genetic contributions to alcohol's reinforcing values. Almost all such studies examine the two-bottle preference test. Despite the deficiencies I have raised in its interpretation, a rodent genotype's willingness to drink ethanol when water is freely available offers a reasonable aggregate estimate of alcohol's reinforcing value relative to other genotypes (Green and Grahame 2008). As indicated above, however, preference drinking studies will likely never avoid the confounding role of taste preferences and most often yield intake levels not sufficient to yield a pharmacologically significant BAL. Thus, the quest for improved measures of reinforcing value continues. Of the potential motivational factors considered by McClearn in his seminal review in this series, we can safely conclude that rodent alcohol drinking is not primarily directed at obtaining calories. The role of taste (and odor) remains a challenge. McClearn appears to have been correct that especially those genotypes that avoid alcohol are probably doing so based on preingestive sensory cues; however, postingestive consequences are also important. Cunningham's intragastric model shows the role of both preingestional and postingestional modulating factors for the best known examples, the usually nearly absolutely alcohol-avoiding DBA/2J and HAP-2 mice. Much subsequent data reinforce McClearn's earlier conclusion that C57BL/6J mice, at least, do not regulate their intake around a given self-administered dose of alcohol by adjusting their intake. This leaves us with the puzzle of why nearly all genotypes, even those directionally selectively bred for high voluntary intake for many generations, fail to self-administer intoxicating amounts of alcohol. Since McClearn's review, many ingenious assays to index alcohol's motivational effects have been used extensively, and new methods for inducing dependence have supplanted the older ones prevalent in 1968. I have tried to identify promising areas where the power of genetics could be fruitfully harvested and generally feel that we have a much more clear idea now about some important experiments remaining to be performed.
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Affiliation(s)
- John C. Crabbe
- Portland Alcohol Research Center, Department of Behavioral Neuroscience, Oregon Health & Science University, and VA Medical Center (R&D 12), 3710 SW US Veterans Hospital Road, Portland, Oregon 97239 USA, Phone: 503-273-5298, FAX: 503-721-1029
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32
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Butler TR, Chappell AM, Weiner JL. Effect of β3 adrenoceptor activation in the basolateral amygdala on ethanol seeking behaviors. Psychopharmacology (Berl) 2014; 231:293-303. [PMID: 23955701 PMCID: PMC3877711 DOI: 10.1007/s00213-013-3238-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Accepted: 07/31/2013] [Indexed: 01/15/2023]
Abstract
RATIONALE The interaction between ethanol (EtOH) and anxiety plays an integral role in the development and maintenance of alcoholism. Many medications in pre-clinical or clinical trials for the treatment of alcoholism share anxiolytic properties. However, these drugs typically have untoward side effects, such as sedation or impairment of motor function that may limit their clinical use. We have recently demonstrated that BRL 37344 (BRL), a selective β3-adrenoceptor (AR) agonist, enhances a discrete population of GABAergic synapses in the basolateral amygdala (BLA) that mediates feed-forward inhibition from lateral paracapsular (LPC) GABAergic interneurons onto BLA pyramidal cells. Behavioral studies revealed that intra-BLA infusion of BRL significantly reduced measures of unconditioned anxiety-like behavior without locomotor depressant effects. OBJECTIVES The present studies tested the effect of BRL (0.1, 0.5, or 1.0 μg/side) on EtOH self-administration using an intermittent access home cage two-bottle choice procedure and limited access operant responding for EtOH or sucrose. RESULTS Intra-BLA infusion of BRL did not reduce home cage, intermittent EtOH self-administration. However, using an operant procedure that permits the discrete assessment of appetitive (seeking) and consummatory measures of EtOH self-administration, BRL reduced measures of EtOH and sucrose seeking, but selectively reduced operant responding for EtOH during extinction probe trials. BRL had no effect on consummatory behaviors for EtOH or sucrose. CONCLUSIONS Together, these data suggest that intra-BLA infusion of BRL significantly reduces motivation to seek EtOH and provide initial evidence that β3-ARs and LPC GABAergic synapses may represent promising targets for the development of novel pharmacotherapies for the treatment of alcoholism.
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Affiliation(s)
- T R Butler
- Department of Physiology and Pharmacology, Wake Forest School of Medicine, Medical Center Boulevard, Winston-Salem, NC, 27157, USA
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Crabbe JC, Metten P, Belknap JK, Spence SE, Cameron AJ, Schlumbohm JP, Huang LC, Barkley-Levenson AM, Ford MM, Phillips TJ. Progress in a replicated selection for elevated blood ethanol concentrations in HDID mice. GENES BRAIN AND BEHAVIOR 2013; 13:236-46. [PMID: 24219304 DOI: 10.1111/gbb.12105] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Revised: 10/09/2013] [Accepted: 11/10/2013] [Indexed: 01/28/2023]
Abstract
Drinking in the dark (DID) is a limited access ethanol-drinking phenotype in mice. High Drinking in the Dark (HDID-1) mice have been bred for 27 selected generations (S27) for elevated blood ethanol concentrations (BECs) after a 4-h period of access to 20% ethanol. A second replicate line (HDID-2) was started later from the same founder population and is currently in S20. An initial report of response to selection in HDID-1 was published after S11. This article reports genetic and behavioral characteristics of both lines in comparison with the HS controls. Heritability is low in both replicates (h(2) = 0.09) but the lines have shown 4-5 fold increases in BEC since S0; 80% of HDID-1 and 60% of HDID-2 mice reach BECs greater than 1.0 mg/ml. Several hours after a DID test, HDID mice show mild signs of withdrawal. Although not considered during selection, intake of ethanol (g/kg) during the DID test increased by approximately 80% in HDID-1 and 60% in HDID-2. Common genetic influences were more important than environmental influences in determining the similarity between BEC and intake for HDID mice. Analysis of the partitioning of intake showed that 60% of intake is concentrated in the last 2 h of the 4 h session. However, this has not changed during selection. Hourly BECs during the DID test reach peak levels after 3 or 4 h of drinking. HDID mice do not differ from HS mice in their rate of elimination of an acute dose of alcohol.
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Affiliation(s)
- J C Crabbe
- Portland Alcohol Research Center; Veterans Affairs Medical Center; Department of Behavioral Neuroscience
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Bass CE, Grinevich VP, Gioia D, Day-Brown JD, Bonin KD, Stuber GD, Weiner JL, Budygin EA. Optogenetic stimulation of VTA dopamine neurons reveals that tonic but not phasic patterns of dopamine transmission reduce ethanol self-administration. Front Behav Neurosci 2013; 7:173. [PMID: 24324415 PMCID: PMC3840465 DOI: 10.3389/fnbeh.2013.00173] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2013] [Accepted: 11/05/2013] [Indexed: 01/16/2023] Open
Abstract
There is compelling evidence that acute ethanol exposure stimulates ventral tegmental area (VTA) dopamine cell activity and that VTA-dependent dopamine release in terminal fields within the nucleus accumbens plays an integral role in the regulation of ethanol drinking behaviors. Unfortunately, due to technical limitations, the specific temporal dynamics linking VTA dopamine cell activation and ethanol self-administration are not known. In fact, establishing a causal link between specific patterns of dopamine transmission and ethanol drinking behaviors has proven elusive. Here, we sought to address these gaps in our knowledge using a newly developed viral-mediated gene delivery strategy to selectively express Channelrhodopsin-2 (ChR2) on dopamine cells in the VTA of wild-type rats. We then used this approach to precisely control VTA dopamine transmission during voluntary ethanol drinking sessions. The results confirmed that ChR2 was selectively expressed on VTA dopamine cells and delivery of blue light pulses to the VTA induced dopamine release in accumbal terminal fields with very high temporal and spatial precision. Brief high frequency VTA stimulation induced phasic patterns of dopamine release in the nucleus accumbens. Lower frequency stimulation, applied for longer periods mimicked tonic increases in accumbal dopamine. Notably, using this optogenetic approach in rats engaged in an intermittent ethanol drinking procedure, we found that tonic, but not phasic, stimulation of VTA dopamine cells selectively attenuated ethanol drinking behaviors. Collectively, these data demonstrate the effectiveness of a novel viral targeting strategy that can be used to restrict opsin expression to dopamine cells in standard outbred animals and provide the first causal evidence demonstrating that tonic activation of VTA dopamine neurons selectively decreases ethanol self-administration behaviors.
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Affiliation(s)
- Caroline E Bass
- Department of Pharmacology and Toxicology, School of Medicine and Biomedical Sciences, University at Buffalo Buffalo, NY, USA
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Nylander I, Roman E. Is the rodent maternal separation model a valid and effective model for studies on the early-life impact on ethanol consumption? Psychopharmacology (Berl) 2013; 229:555-69. [PMID: 23982922 PMCID: PMC3782650 DOI: 10.1007/s00213-013-3217-3] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2013] [Accepted: 07/10/2013] [Indexed: 12/18/2022]
Abstract
RATIONALE Early-life events can cause long-term neurobiological and behavioural changes with a resultant effect upon reward and addiction processes that enhance risk to develop alcohol use disorders. Maternal separation (MS) is used to study the mediating mechanisms of early-life influences in rodents. In MS studies, the pups are exposed to maternal absence during the first postnatal weeks. The outcome of MS experiments exhibits considerable variation and questions have been raised about the validity of MS models. OBJECTIVES This short review aims to provide information about experimental conditions that are important to consider when assessing the impact of early-life environment on voluntary ethanol consumption. RESULTS The results from currently used MS protocols are not uniform. However, studies consistently show that longer separations of intact litters predispose for higher ethanol consumption and/or preference in adult male rats as compared to shorter periods of MS. Studies using individual pup MS paradigms, other controls, low ethanol concentrations, adult females or examining adolescent consumption reported no differences or inconsistent results. CONCLUSIONS There is no "a rodent MS model", there are several models and they generate different results. The compiled literature shows that MS is a model of choice for analysis of early-life effects on voluntary ethanol consumption but there are examples of MS paradigms that are not suitable. These studies emphasize the importance to carefully designed MS experiments to supply the optimal conditions to definitely test the research hypothesis and to be particulate in the interpretation of the outcome.
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Affiliation(s)
- Ingrid Nylander
- Department of Pharmaceutical Biosciences, Neuropharmacology Addiction & Behaviour, Uppsala University, Box 591, 751 24, Uppsala, Sweden,
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Roberts DCS, Gabriele A, Zimmer BA. Conflation of cocaine seeking and cocaine taking responses in IV self-administration experiments in rats: methodological and interpretational considerations. Neurosci Biobehav Rev 2013; 37:2026-36. [PMID: 23669047 DOI: 10.1016/j.neubiorev.2013.04.017] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Revised: 04/19/2013] [Accepted: 04/30/2013] [Indexed: 01/13/2023]
Abstract
IV drug self-administration is a special case of an operant task. In most operant experiments, the instrumental response that completes the schedule requirement is separate and distinct from the consumptive response (e.g. eating or drinking) that follows the delivery of the reinforcing stimulus. In most IV self-administration studies drug seeking and drug taking responses are conflated. The instrumental lever press or nose poke is also a consumptive response. The conflation of these two response classes has important implications for interpretation of the data as they are differentially regulated by dose and price. The types of pharmacological pretreatments that affect appetitive responses are not necessarily the same as those that affect consumptive responses suggesting that the neurobiology of the two response classes are to some extent controlled by different mechanisms. This review discusses how schedules of reinforcement and behavioral economic analyses can be used to assess the regulation of drug seeking and drug taking separately. New methods are described that allow the examination of appetitive or consumptive responding in isolation and provide subjects with greater control over the self-administered dose. These procedures provide novel insights into the regulation of drug intake. Cocaine intake patterns that result in large, intermittent spikes in cocaine levels are shown to produce increases in appetitive responding (i.e. drug seeking). The mechanisms that control drug intake should be considered distinct from appetitive and motivational processes and should be taken into consideration in future IV self-administration studies.
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Affiliation(s)
- David C S Roberts
- Department of Physiology and Pharmacology, Wake Forest Health Sciences, Winston-Salem, NC 27101, USA.
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Broadwater M, Varlinskaya EI, Spear LP. Effects of voluntary access to sweetened ethanol during adolescence on intake in adulthood. Alcohol Clin Exp Res 2012; 37:1048-55. [PMID: 23278242 DOI: 10.1111/acer.12049] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Accepted: 10/22/2012] [Indexed: 11/30/2022]
Abstract
BACKGROUND The prevalence of alcohol use during adolescence is concerning given that early age of alcohol initiation is correlated with the development of alcohol-related problems later in life. The purpose of this series of studies was to assess whether voluntary ethanol (EtOH) exposure during adolescence would influence EtOH drinking behavior in adulthood using an animal model. METHODS Pair-housed Sprague-Dawley adolescent (postnatal day [P] 28 to 42) rats of both sexes were given single bottle access to 1 of 3 solutions in their home cages-10% EtOH in "supersac" (0.125% saccharin and 3% sucrose) (EtOH/SS), supersac without EtOH (SS), or water-for 30 minutes every other day for a total of 8 drinking days or were left nonmanipulated (NM). Animals were NM thereafter until adulthood (P70) at which time they were given 1-bottle, 30 minute limited access tests with 20% EtOH every other day (Exp 1), 10% EtOH in SS (Exp 2), or SS without EtOH (Exp 3). RESULTS Adolescent EtOH/SS exposure increased adulthood consumption of EtOH/SS (Exp 2), but not 20% unsweetened EtOH (Exp 1) or SS (Exp 3), with this increase most pronounced at the beginning of the 8 intake day procedure. Access to SS (without EtOH) during adolescence produced an analogous effect, with increased adult SS consumption during the first 2 intake days, but no increases in either of the EtOH test solutions. CONCLUSIONS Solution-specific increases in adulthood intake after adolescent exposure are most likely associated with solution acceptance due to familiarity. This is an important consideration for future intake studies assessing the influence of EtOH exposure during adolescence on intake of EtOH in adulthood.
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Affiliation(s)
- Margaret Broadwater
- Department of Psychology, Center for Development and Behavioral Neuroscience, Binghamton University, Binghamton, NY 13902, USA
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Bell RL, Sable HJ, Colombo G, Hyytia P, Rodd ZA, Lumeng L. Animal models for medications development targeting alcohol abuse using selectively bred rat lines: neurobiological and pharmacological validity. Pharmacol Biochem Behav 2012; 103:119-55. [PMID: 22841890 PMCID: PMC3595005 DOI: 10.1016/j.pbb.2012.07.007] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Revised: 07/07/2012] [Accepted: 07/18/2012] [Indexed: 02/04/2023]
Abstract
The purpose of this review paper is to present evidence that rat animal models of alcoholism provide an ideal platform for developing and screening medications that target alcohol abuse and dependence. The focus is on the 5 oldest international rat lines that have been selectively bred for a high alcohol-consumption phenotype. The behavioral and neurochemical phenotypes of these rat lines are reviewed and placed in the context of the clinical literature. The paper presents behavioral models for assessing the efficacy of pharmaceuticals for the treatment of alcohol abuse and dependence in rodents, with particular emphasis on rats. Drugs that have been tested for their effectiveness in reducing alcohol/ethanol consumption and/or self-administration by these rat lines and their putative site of action are summarized. The paper also presents some current and future directions for developing pharmacological treatments targeting alcohol abuse and dependence.
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Affiliation(s)
- Richard L. Bell
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Helen J.K. Sable
- Department of Psychology, University of Memphis, Memphis, Tennessee, USA
| | - Giancarlo Colombo
- Neuroscience Institute, National Research Council of Italy, Section of Cagliari, Monserrato, Italy
| | - Petri Hyytia
- Institute of Biomedicine, University of Helsinki, Finland
| | - Zachary A. Rodd
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Lawrence Lumeng
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA
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Chappell AM, Carter E, McCool BA, Weiner JL. Adolescent rearing conditions influence the relationship between initial anxiety-like behavior and ethanol drinking in male Long Evans rats. Alcohol Clin Exp Res 2012; 37 Suppl 1:E394-403. [PMID: 22924742 DOI: 10.1111/j.1530-0277.2012.01926.x] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Accepted: 06/21/2012] [Indexed: 01/25/2023]
Abstract
BACKGROUND Rodent studies have demonstrated that adolescent social isolation results in many behavioral perturbations, including increases in anxiety-like behaviors. Socially isolated (SI) rats have also been shown to self-administer greater amounts ethanol (EtOH) in some, but not all, studies. Here, we tested whether juvenile social isolation increases EtOH drinking using an intermittent procedure that engenders relatively high intake in normally reared animals. We also compared the behavioral phenotype of rats reared under social isolation or group-housed conditions with adult rats housed under conditions commonly used in EtOH-drinking studies. METHODS Male Long Evans rats were procured immediately postweaning and were group housed for 1 week. Subjects were then randomly divided into 2 groups: SI rats, housed individually for 6 weeks and group-housed (GH) rats (4/cage). A third group was procured as young adults and was housed individually upon arrival for 1 week (standard housing condition). Rats were then tested in a plus-maze and novelty assay, and then, all subjects were singly housed and EtOH drinking was assessed. RESULTS SI rats displayed increased anxiety-like behaviors on the plus-maze, a greater locomotor response to a novel environment, and increased EtOH intake, relative to GH rats. Age-matched standard housed (STD) rats exhibited an anxiety-like behavioral profile on the plus-maze that was similar to SI, and not GH rats, and also drank EtOH at levels comparable with SI subjects. In addition, anxiety-like behavior on the plus-maze correlated with intermittent EtOH intake in SI and GH rats. CONCLUSIONS These data further support the validity of the rodent juvenile social isolation model for studies directed at elucidating behavioral and neurobiological mechanisms linking anxiety and EtOH drinking. These findings further suggest that housing conditions commonly employed in rodent drinking studies may recapitulate the anxiety-like and EtOH-drinking phenotype engendered by a juvenile social isolation procedure.
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Affiliation(s)
- Ann M Chappell
- Department of Physiology and Pharmacology, Wake Forest University School of Medicine, Medical Center Boulevard, Winston-Salem, North Carolina 27157, USA
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Miranda-Morales RS, Spear NE, Nizhnikov ME, Molina JC, Abate P. Role of mu, delta and kappa opioid receptors in ethanol-reinforced operant responding in infant rats. Behav Brain Res 2012; 234:267-77. [PMID: 22789403 DOI: 10.1016/j.bbr.2012.07.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 06/30/2012] [Accepted: 07/04/2012] [Indexed: 01/03/2023]
Abstract
We recently observed that naloxone, a non-specific opioid antagonist, attenuated operant responding to ethanol in infant rats. Through the use of an operant conditioning technique, we aimed to analyze the specific participation of mu, delta, and kappa opioid receptors on ethanol reinforcement during the second postnatal week. In Experiment 1, infant rats (PDs 14-17) were trained to obtain 5, 7.5, 10, or 15% ethanol, by operant nose-poking. Experiment 2 tested blood ethanol levels (BELs) attained by operant behavior. In Experiment 3, at PDs 16-18, rats received CTOP (mu antagonist: 0.1 or 1.0 mg/kg), naltrindole (delta antagonist: 1.0 or 5.0 mg/kg) or saline before training. In Experiment 4, rats received nor-binaltorphimine (kappa antagonist: 10.0 or 30.0 mg/kg, a single injection after completion of PD 15 operant training), spiradoline mesylate (kappa agonist: 1.0 or 5.0 mg/kg; at PDs 16-18) or saline (PDs 16-18), before the conditioning. Experiments 5 and 6 assessed possible side effects of opioid drugs in locomotor activity (LA) and conditioned taste aversion (CTA). Ethanol at 7.5 and 10% promoted the highest levels of operant responding. BELs were 12-15 mg/dl. In Experiment 3 naltrindole (dose-response effect) and CTOP (the lowest dose) were effective in decreasing operant responding. Nor-binaltorphimine at 10.0 mg/kg and spiradoline at 5.0 mg/kg also blocked ethanol responding. The effects of opioid drugs on ethanol reinforcement cannot be explained by effects on LA or CTA. Even though particular aspects of each opioid receptor require further testing, a fully functional opioid system seems to be necessary for ethanol reinforcement, during early ontogeny.
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Shabani S, Dobbs LK, Ford MM, Mark GP, Finn DA, Phillips TJ. A genetic animal model of differential sensitivity to methamphetamine reinforcement. Neuropharmacology 2012; 62:2169-77. [PMID: 22280875 PMCID: PMC3320769 DOI: 10.1016/j.neuropharm.2012.01.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Revised: 12/19/2011] [Accepted: 01/04/2012] [Indexed: 01/26/2023]
Abstract
Sensitivity to reinforcement from methamphetamine (MA) likely influences risk for MA addiction, and genetic differences are one source of individual variation. Generation of two sets of selectively bred mouse lines for high and low MA drinking has shown that genetic factors influence MA intake, and pronounced differences in sensitivity to rewarding and aversive effects of MA play a significant role. Further validation of these lines as a unique genetic model relevant to MA addiction was obtained using operant methods to study MA reinforcement. High and low MA drinking line mice were used to test the hypotheses that: 1) oral and intracerebroventricular (ICV) MA serve as behavioral reinforcers, and 2) MA exhibits greater reinforcing efficacy in high than low MA drinking mice. Operant responses resulted in access to an MA or non-MA drinking tube or intracranial delivery of MA. Behavioral activation consequent to orally consumed MA was determined. MA available for consumption maintained higher levels of reinforced instrumental responding in high than low MA drinking line mice, and MA intake in the oral operant procedure was greater in high than low MA drinking line mice. Behavioral activation was associated with amount of MA consumed during operant sessions. High line mice delivered more MA via ICV infusion than did low line mice across a range of doses. Thus, genetic risk factors play a critical role in the reinforcing efficacy of MA and the oral self-administration procedure is suitable for delineating genetic contributions to MA reinforcement.
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Affiliation(s)
- Shkelzen Shabani
- Department of Behavioral Neuroscience and Methamphetamine Abuse Research Center, Oregon Health & Science University, Portland, OR 97239
| | - Lauren K Dobbs
- Department of Behavioral Neuroscience and Methamphetamine Abuse Research Center, Oregon Health & Science University, Portland, OR 97239
| | - Matthew M Ford
- Department of Behavioral Neuroscience and Methamphetamine Abuse Research Center, Oregon Health & Science University, Portland, OR 97239
| | - Gregory P Mark
- Department of Behavioral Neuroscience and Methamphetamine Abuse Research Center, Oregon Health & Science University, Portland, OR 97239
| | - Deborah A Finn
- Department of Behavioral Neuroscience and Methamphetamine Abuse Research Center, Oregon Health & Science University, Portland, OR 97239
- Veterans Affairs Medical Center, Portland, OR 97239
| | - Tamara J Phillips
- Department of Behavioral Neuroscience and Methamphetamine Abuse Research Center, Oregon Health & Science University, Portland, OR 97239
- Veterans Affairs Medical Center, Portland, OR 97239
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Naloxone attenuation of ethanol-reinforced operant responding in infant rats in a re-exposure paradigm. Psychopharmacology (Berl) 2012; 219:235-46. [PMID: 21750896 DOI: 10.1007/s00213-011-2402-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/18/2010] [Accepted: 06/17/2011] [Indexed: 12/23/2022]
Abstract
RATIONALE Early ethanol exposure promotes ethanol reinforcement, mediated perhaps by ethanol's motivational effects. The opioid system mediates ethanol reinforcement, at least in part. OBJECTIVES Modulation of consummatory and seeking behaviors by the opioid system was tested in terms of ethanol or sucrose operant self-administration. METHODS Wistar-derived infant rats were tested in an operant conditioning task. (1) Infants were trained on postnatal days (PDs) 14-17 to obtain 5% sucrose and 3.75% ethanol or water, and evaluated in an extinction session at PD 18. (2) Ethanol (3.75%) was used as reinforcer. At PDs 16-17, 6 h before operant task, pups were re-exposed to ethanol after naloxone injection (0 or 1 mg/kg). (3) Sucrose (5%) acted as reinforcer. Pups were re-exposed to sucrose after naloxone injection. (4) A PD 18 re-exposure trial in which pups were injected with naloxone and re-exposed to ethanol was added. RESULTS Sucrose and ethanol promoted higher levels of operant responding than water during training and extinction. Re-exposure to ethanol preceded by naloxone decreased nose-poking. A similar profile was observed towards sucrose. No seeking behavior was observed in pups re-exposed to ethanol following naloxone injection during PDs 16-18. CONCLUSIONS Self-administration of ethanol was established in terms of operant responding in preweanling rats with no previous exposure to the drug. Pairing of naloxone with ethanol, at a point separate in time from operant responding, reduced ethanol reinforcement. This indicated participation of the opioid system in ethanol reinforcement. This effect seems not to be unique to ethanol but also is observable when sucrose acts as reinforcer.
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Verplaetse TL, Rasmussen DD, Froehlich JC, Czachowski CL. Effects of prazosin, an α1-adrenergic receptor antagonist, on the seeking and intake of alcohol and sucrose in alcohol-preferring (P) rats. Alcohol Clin Exp Res 2011; 36:881-6. [PMID: 21981346 DOI: 10.1111/j.1530-0277.2011.01653.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND Previous studies show that prazosin, an α(1) -adrenergic receptor antagonist, decreases alcohol drinking in animal models of alcohol use and dependence [Rasmussen et al. (2009) Alcohol Clin Exp Res 3:264-272; Walker et al. (2008) Alcohol 42:91-97] and in alcohol-dependent men [Simpson et al. (2009) Alcohol Clin Exp Res 33:255-263]. This study extended these findings by using a paradigm that allows for separate assessment of prazosin on motivation to seek versus consume alcohol or sucrose in selectively bred rats. METHODS Alcohol-preferring (P) rats were trained to complete an operant response that resulted in access to either 2% sucrose or 10% alcohol. A 4-week Seeking Test Phase examined responding in single, weekly extinction sessions when no reinforcer could be obtained. A 4-week Drinking Test Phase consisted of rats lever-pressing to "pay" a specified amount up front to gain access to unlimited alcohol (or sucrose) for a 20-minute period. On Seeking and Drinking test days, prazosin (0.0, 0.5, 1.0, and 1.5 mg/kg) was administered intraperitoneally 30 minutes prior to behavioral sessions. RESULTS Rats were self-administering an average of 0.9 (±0.09) g/kg alcohol on vehicle test day and had pharmacologically relevant blood ethanol concentrations. Prazosin significantly decreased alcohol seeking at all doses tested. The highest dose of prazosin also increased the latency to first response for alcohol and decreased alcohol intake. While sucrose-seeking and intake were similarly affected by prazosin, the high dose of prazosin did not increase response latency. CONCLUSIONS These findings are consistent with and extend previous research and suggest that prazosin decreases motivation to initiate and engage in alcohol consumption. The specificity of prazosin in attenuating the initiation of alcohol- but not sucrose-seeking suggests that this effect is not because of prazosin-induced motor-impairment or malaise. Together with previous findings, these data suggest that prazosin may be an effective pharmacotherapy, with specific application in people that drink excessively or have a genetic predisposition to alcohol abuse.
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Berg SA, Czachowski CL, Chambers RA. Alcohol seeking and consumption in the NVHL neurodevelopmental rat model of schizophrenia. Behav Brain Res 2010; 218:346-9. [PMID: 21184782 DOI: 10.1016/j.bbr.2010.12.017] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Revised: 12/10/2010] [Accepted: 12/10/2010] [Indexed: 11/30/2022]
Abstract
Alcohol abuse in schizophrenia exceeds rates in the general population and worsens illness outcomes. Neonatal ventral hippocampal lesion (NVHL) rats model multiple schizophrenia dimensions including addiction vulnerability. This study compared NVHL vs. SHAM-controls in operant alcohol seeking and consumption. NVHLs enhanced consumption of combined ethanol/sucrose solution but neither ethanol or sucrose only solutions, consistent with increased vulnerability specific to carbohydrate-laden alcohol beverages typically consumed in early stages of human alcoholism.
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Affiliation(s)
- S A Berg
- Institute of Psychiatric Research, Department of Psychiatry, Indiana University School of Medicine, 791 Union Drive, Indianapolis, IN 46202, USA.
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Miranda-Morales RS, Molina JC, Spear NE, Abate P. Participation of the endogenous opioid system in the acquisition of a prenatal ethanol-related memory: effects on neonatal and preweanling responsiveness to ethanol. Physiol Behav 2010; 101:153-60. [PMID: 20451537 DOI: 10.1016/j.physbeh.2010.04.033] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2009] [Revised: 04/22/2010] [Accepted: 04/28/2010] [Indexed: 10/19/2022]
Abstract
The present study tested the involvement of the opioid system in the acquisition and expression of prenatal ethanol-related memories. We evaluated how this prenatal experience modulates ethanol self-administration in newborn rats, and preweanling's ingestion of the drug. During Gestational Days (GDs) 17-20, four groups of dams were treated with ethanol (2 g/kg) or water, followed immediately by naloxone (10 mg/kg) or saline administration. A fifth group received a similar dose of naloxone 20min before ethanol administration. On PD 1, pups were tested on an operant learning procedure to obtain milk or 3% ethanol. One hour later, an extinction session was performed. At Postnatal Days (PDs) 14 and 15, preweanlings representing each prenatal treatment were evaluated in an intake test with infusions of 5% ethanol or water. Prior to the intake test on PD14, preweanlings were administered naloxone (1 mg/kg), saline or remained untreated. In both tests, animals representative of both genders were utilized. One-day-old pups rapidly learned the operant behavior to gain access to milk. In contrast, only pups prenatally treated with ethanol (administered immediately before naloxone or saline injection) increased operant responding to gain access to ethanol. On an intake test at PDs 14 and 15, those animals prenatally exposed to naloxone 20 min before ethanol administration consumed significantly lower ethanol levels than the remaining prenatal ethanol groups. Postnatal treatment with naloxone diminished intake of all solutions at PD14. These results suggest that prenatal ethanol exposure facilitates neonatal operant learning reinforced by intraoral administration of ethanol and increases ethanol consumption during PDs 14-15. The endogenous opioid system apparently is involved in the acquisition of prenatal ethanol memories, which can modulate the reinforcing attributes of the drug in neonatal and preweanling rats.
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Stephens DN, Duka T, Crombag HS, Cunningham CL, Heilig M, Crabbe JC. Reward sensitivity: issues of measurement, and achieving consilience between human and animal phenotypes. Addict Biol 2010; 15:145-68. [PMID: 20148777 DOI: 10.1111/j.1369-1600.2009.00193.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Reward is a concept fundamental to discussions of drug abuse and addiction. The idea that altered sensitivity to either drug-reward, or to rewards in general, contributes to, or results from, drug-taking is a common theme in several theories of addiction. However, the concept of reward is problematic in that it is used to refer to apparently different behavioural phenomena, and even to diverse neurobiological processes (reward pathways). Whether these different phenomena are different behavioural expressions of a common underlying process is not established, and much research suggests that there may be only loose relationships among different aspects of reward. Measures of rewarding effects of drugs in humans often depend upon subjective reports. In animal studies, such insights are not available, and behavioural measures must be relied upon to infer rewarding effects of drugs or other events. In such animal studies, but also in many human methods established to objectify measures of reward, many other factors contribute to the behaviour being studied. For that reason, studying the biological (including genetic) bases of performance of tasks that ostensibly measure reward cannot provide unequivocal answers. The current overview outlines the strengths and weaknesses of current approaches that hinder the conciliation of cross-species studies of the genetics of reward sensitivity and the dysregulation of reward processes by drugs of abuse. Some suggestions are made as to how human and animal studies may be made to address more closely homologous behaviours, even if those processes are only partly able to isolate 'reward' from other factors contributing to behavioural output.
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Affiliation(s)
- David N Stephens
- Department of Psychology, University of Sussex, Falmer, Brighton BN1 9QG, UK.
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Differential role of mu, delta and kappa opioid receptors in ethanol-mediated locomotor activation and ethanol intake in preweanling rats. Physiol Behav 2009; 99:348-54. [PMID: 19954749 DOI: 10.1016/j.physbeh.2009.11.012] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2009] [Revised: 11/17/2009] [Accepted: 11/24/2009] [Indexed: 11/21/2022]
Abstract
The opioid system modulates ethanol intake and reinforcement in adult and preweanling rodents. While adult heterogeneous rats normally do not show ethanol-mediated locomotor stimulation, preweanling rats show it quite clearly. We recently observed that naloxone, a non-specific opioid antagonist, attenuated ethanol-induced locomotor activation in preweanling rats. In the present study we tested the role of specific opioid receptors (mu, delta and kappa) in ethanol-mediated locomotor stimulation and ethanol intake. In Experiment 1 13-day-old rats received naloxonazine (mu antagonist: 0, 7.5 or 15 mg/kg), naltrindole (delta antagonist: 0, 2 or 4 mg/kg) or nor-binaltorphimine (kappa antagonist: 0, 2, 4 or 8 mg/kg) before an intragastric administration of ethanol (0 or 2.5 g/kg), and subsequent locomotor activity assessment. In Experiment 2, the same opioid antagonists were administered on postnatal days 13 and 14 before consumption of ethanol (6%), saccharin (0.05%) or distilled water. In Experiment 1 only naloxonazine reduced ethanol-mediated locomotor stimulation. None of the opioid antagonists affected locomotor activity in water controls. In Experiment 2 naloxonazine and naltrindole suppressed ingestion of all the solutions tested. Similar to what has been reported in adult rodents, mu-opioid receptors seem to modulate ethanol-activating effects during early ontogeny. Hence, there seems to be a partial overlap of neurochemical mechanisms involved in the rewarding and stimulating effects of ethanol in preweanling rats. Mu-receptor antagonists reduced both ethanol-induced activity and ethanol intake, but it is unclear whether the latter effect is specific to ethanol or only a reflection of an effect on consummatory behavior generally, since mu and delta receptor antagonists also suppressed ingestion of water and saccharin.
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March SM, Abate P, Spear NE, Molina JC. Fetal exposure to moderate ethanol doses: heightened operant responsiveness elicited by ethanol-related reinforcers. Alcohol Clin Exp Res 2009; 33:1981-93. [PMID: 19719792 PMCID: PMC3085171 DOI: 10.1111/j.1530-0277.2009.01037.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Prenatal exposure to moderate ethanol doses during late gestation modifies postnatal ethanol palatability and ingestion. The use of Pavlovian associative procedures has indicated that these prenatal experiences broaden the range of ethanol doses capable of supporting appetitive conditioning. Recently, a novel operant technique aimed at analyzing neonatal predisposition to gain access to ethanol has been developed. Experiment 1 tested the operant conditioning technique for developing rats described by Arias and colleagues (2007) and Bordner and colleagues (2008). In Experiment 2, we analyzed changes in the disposition to gain access to ethanol as a result of moderate prenatal exposure to the drug. METHODS In Experiment 1, newborn pups were intraorally cannulated and placed in a supine position that allowed access to a touch-sensitive sensor. Paired pups received an intraoral administration of a given reinforcer (milk or quinine) contingent upon physical contact with the sensor. Yoked controls received similar reinforcers only when Paired pups activated the circuit. In Experiment 2, natural reinforcers (water or milk) as well as ethanol (3% or 6% v/v) or an ethanol-related reinforcer (sucrose compounded with quinine) were tested. In this experiment, pups had been exposed to water or ethanol (1 or 2 g/kg) during gestational days 17 to 20. RESULTS Experiment 1 confirmed previous results showing that 1-day-old pups rapidly learn an operant task to gain access to milk, but not to gain access to a bitter tastant. Experiment 2 showed that water and milk were highly reinforcing across prenatal treatments. Furthermore, general activity during training was not affected by prenatal exposure to ethanol. Most importantly, prenatal ethanol exposure facilitated conditioning when the reinforcer was 3% v/v ethanol or a psychophysical equivalent of ethanol's gustatory properties (sucrose-quinine). CONCLUSIONS The present results suggest that late prenatal experience with ethanol changes the predisposition of the newborn to gain access to ethanol-related stimuli. In conjunction with prior literature, this study emphasizes the fact that intrauterine experience with ethanol not only augments ethanol's palatability and ingestion, but also facilitates the acquisition of response-stimulus associations where the drug acts as an intraoral reinforcer.
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Affiliation(s)
- Samanta M. March
- Instituto de Investigación Médica M. y M. Ferreyra (INIMEC – CONICET), Córdoba, Argentina
- Facultad de Psicología, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Paula Abate
- Instituto de Investigación Médica M. y M. Ferreyra (INIMEC – CONICET), Córdoba, Argentina
- Facultad de Psicología, Universidad Nacional de Córdoba, Córdoba, Argentina
| | - Norman E. Spear
- Center for Developmental Psychobiology, Binghamton University, Binghamton, NY, USA
| | - Juan Carlos Molina
- Instituto de Investigación Médica M. y M. Ferreyra (INIMEC – CONICET), Córdoba, Argentina
- Center for Developmental Psychobiology, Binghamton University, Binghamton, NY, USA
- Facultad de Psicología, Universidad Nacional de Córdoba, Córdoba, Argentina
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Central urocortin 3 administration decreases limited-access ethanol intake in nondependent mice. Behav Pharmacol 2009; 20:346-51. [PMID: 19581799 DOI: 10.1097/fbp.0b013e32832f01ba] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Stress and alcohol abuse are co-related. Acute alcohol is anxiolytic and stress is cited as a factor in relapse to alcohol use. A primary mediator of the stress response is the neuropeptide corticotropin-releasing factor (CRF). The CRF family of endogenous ligands includes urocortin 3 (Ucn 3), which binds selectively to the CRF type 2 receptor and has been implicated in ethanol consumption in dependent and withdrawing rats. The objective of this study was to examine the effect of Ucn 3, delivered centrally to nondependent mice, on limited-access ethanol consumption. Adult C57BL/6J mice were trained to self-administer 10% ethanol during daily, 2-h limited-access sessions, using lickometers to assess drinking patterns for both ethanol and water. Sterile saline or 0.3, 1, or 3 nmol of Ucn 3 was microinjected into the lateral ventricle immediately before the limited-access session in a within-subjects design. There was a significant decrease in ethanol (both ml and g/kg), but not water, intake following Ucn 3 treatment, explained by a change in size of the largest lick run. Food intake at both 2 h and 24 h after injection was statistically unaffected by Ucn 3 administration. These results establish a role for CRF type 2 receptors in a nondependent mouse model of ethanol self-administration.
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